Add new port: imagemagick image manipulation library

[Greisby]

ImageMagick is a widely-used, battle-tested C/C++ library and tool suite for creating, editing, composing, and converting digital images.
It supports hundreds of image formats (JPEG, PNG, TIFF, WebP, HEIC, AVIF, OpenEXR, JPEG XL, …), color management, drawing, compositing, and transforms.

It may be used directly by FFmpeg (via the image2 demuxer/muxer and the overlay filter fallback), Ghostscript interop, and countless image-processing pipelines.

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Draft notice: this PR depends on PR #51725 - it will stay in Draft until that PR is merged.

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Why this new vcpkg port?

There is currently no official imagemagick port in vcpkg.
This PR adds one from scratch, with full autotools support on Linux/macOS/Windows and specific fixes to make the MSVC/cl.exe toolchain work correctly under MSYS2.

Key additions vs. a naive autotools port:

• CMake IMPORTED targets (ImageMagick::Magick++, ImageMagick::MagickWand, ImageMagick::MagickCore) with compile-definitions automatically propagated to consumers
• #warning → #pragma message fix for MSVC (cl.exe does not accept #warning)
• Quantum depth (q8 / q16 / q32) and HDRI as first-class vcpkg features
• Proper delegate library wiring: every optional format dependency is either an unconditional vcpkg dependency or explicitly disabled - no silent system-library probing
• A cl_wrapper.sh / lib_wrapper.sh pair that translates GCC-style libtool invocations to MSVC-compatible flags so the standard autotools+libtool flow works with cl.exe

Port contents

Features

The port exposes a rich set of vcpkg features, all wired to explicit --with-* / --without-* configure flags so no uncontrolled system-library discovery can occur.
I think that I didn't forgot any of the dependencies already available in vcpkg.

Quantum depth (mutually exclusive, exactly one must be selected):

Feature	Configure flag	Default
q8	--with-quantum-depth=8	-
q16	--with-quantum-depth=16	Yes
q32	--with-quantum-depth=32	-

Quantum depth is ABI-breaking: q8, q16, and q32 builds produce incompatible library variants (suffix Q8, Q16HDRI, Q32HDRI, …).
Consumers must be compiled with the same depth.

Pixel processing:

Feature	Description	Default
hdri	High Dynamic Range Imaging (floating-point pixels)	Yes
zero-configuration	Embed XML config in binary; no runtime XML files	-
openmp	OpenMP parallel processing (MSVC, GCC; not clang)	-

Delegate / format libraries:

Feature	Description	Default
bzip2	BZip2 compression	Yes
lzma	LZMA compression	Yes
zstd	Zstandard compression	Yes
jpeg	JPEG format (libjpeg-turbo)	Yes
png	PNG format (libpng)	Yes
tiff	TIFF format	Yes
webp	WebP format	Yes
lcms	Little CMS color management	Yes
xml2	XML/SVG support	Yes
freetype	FreeType font rendering	-
fontconfig	Font discovery	-
openexr	OpenEXR HDR format	-
openjp2	JPEG 2000 format (openjpeg)	-
heif	HEIF/HEIC/AVIF format	-
jxl	JPEG XL format	-
raw	RAW photo format (libraw)	-
jbig	JBIG lossless compression	-
fftw	Discrete Fourier Transform (fftw3)	-
pango	Complex text layout via Pango	-
raqm	Complex text layout via libraqm	-
rsvg	SVG rendering via librsvg	-
gvc	Graphviz support	-
zip	Zip archive support	-
x11	X Window System (Linux/macOS only)	-
uhdr	Ultra HDR (libultrahdr, not yet in vcpkg)	-

Meta-features (convenience bundles):

Feature	Pulls in
modern-formats	heif, jxl, webp
professional-formats	openexr, openjp2, raw

Patches

Patch	Purpose
0001-fix-zstd-pkgconfig-prefix.patch	Fix zstd pkg-config prefix so autoconf finds it correctly
0002-fix-fallthrough-msvc-c-mode.patch	Force C++ compilation for EMF coder (uses [[fallthrough]])
0003-fix-cppflags-crt-conflict.patch	Prevent CRT flags from leaking into CPPFLAGS on MSVC
0004-fix-uhdr-cpp-compat.patch	C++ compatibility fix for Ultra HDR delegate
0005-fix-warning-directive-msvc.patch	Replace #warning with #pragma message (cl.exe requirement)
0006-fix-winpathscript-init-order.patch	Fix Windows path-script initialization order in autotools

CMake integration

The port installs a hand-crafted imagemagick-config.cmake that exposes:

find_package(imagemagick CONFIG REQUIRED)
target_link_libraries(my_app PRIVATE ImageMagick::Magick++)
# Automatically propagates:
#   MAGICKCORE_QUANTUM_DEPTH=16  (or 8/32 from selected feature)
#   MAGICKCORE_HDRI_ENABLE=1     (when hdri feature is on)

Available targets: ImageMagick::MagickCore, ImageMagick::MagickWand, ImageMagick::Magick++.

Platform support

Platform	Status	Notes
Windows x64 MSVC v143	✅ tested	cl_wrapper.sh + lib_wrapper.sh bridge libtool ↔ cl.exe/lib.exe
Windows x64 clang-cl	✅ tested	cl_wrapper.sh + lib_wrapper.sh bridge libtool ↔ cl.exe/lib.exe
Linux x64 gcc.	✅ tested	Standard autotools flow
Linux x64 clang.	✅ tested	Standard autotools flow
macOS arm64	✅ tested	Standard autotools flow

I rely on the CIs of vcpkg to test the others…

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• Changes comply with the maintainer guide.
• The packaged project shows strong association with the chosen port name. Check this box if at least one of the following criteria is met:
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• Optional dependencies of the build are all controlled by the port. A dependency is controlled if it is declared an unconditional dependency in vcpkg.json, or explicitly disabled through patches or build system arguments such as CMAKE_DISABLE_FIND_PACKAGE_Xxx or VCPKG_LOCK_FIND_PACKAGE
• The versioning scheme in vcpkg.json matches what upstream says.
• The license declaration in vcpkg.json matches what upstream says.
• The installed as the "copyright" file matches what upstream says.
• The source code of the component installed comes from an authoritative source.
• The generated "usage text" is brief and accurate. See adding-usage for context. Don't add a usage file if the automatically generated usage is correct.
• The version database is fixed by rerunning ./vcpkg x-add-version --all and committing the result.
• Exactly one version is added in each modified versions file.

[talregev]

We have GraphicsMagick port.
These ports can coexist? Are they both have the same libraries files names?

Note for maintainers to check that.

[dg0yt]

Are these PRs assisted by AI? Too many at once may discourage good reviews.