Add macOS (Apple Silicon) build support

[mossishahi]

Summary

Minimal changes to enable building Video2X on macOS with Apple Silicon (M1/M2/M3/M4) using Homebrew dependencies and MoltenVK.

• CMakeLists.txt: Add OpenMP discovery (find_package(OpenMP)), skip Linux-only linker flags (--gc-sections, -Wl,-s) on Apple, add Homebrew lib path
• vulkan_utils.cpp: Enable VK_KHR_portability_enumeration extension required by MoltenVK to enumerate Vulkan devices on macOS

Changes

Only 2 files, 14 lines added/changed. No new dependencies. No breaking changes for Linux/Windows.

Build instructions (macOS)

brew install ffmpeg libomp boost vulkan-headers vulkan-loader spdlog ncnn cmake ninja pkg-config just
export OpenMP_ROOT=/opt/homebrew/opt/libomp
cmake -G Ninja -S . -B build     -DCMAKE_CXX_COMPILER=clang++     -DCMAKE_BUILD_TYPE=Release     -DCMAKE_INSTALL_PREFIX=build/install     -DVIDEO2X_ENABLE_NATIVE=ON     -DOpenMP_CXX_FLAGS="-Xpreprocessor -fopenmp -I/opt/homebrew/opt/libomp/include"     -DOpenMP_CXX_LIB_NAMES="omp"     -DOpenMP_omp_LIBRARY=/opt/homebrew/opt/libomp/lib/libomp.dylib     -DVulkan_INCLUDE_DIR=/opt/homebrew/include     -DVulkan_LIBRARY=/opt/homebrew/lib/libvulkan.dylib
cmake --build build --config Release --parallel --target install

Test environment

• MacBook Air, Apple M3, macOS 26.3 (Tahoe)
• All 4 processors tested: Real-ESRGAN (4x upscale), Real-CUGAN, RIFE (frame interpolation), libplacebo (Anime4K)
• GPU detected via MoltenVK: Apple M3 (Vulkan 1.0.334)

References

Addresses #1189 — based on the patch shared by @savar in that thread, cleaned up and verified on current master.

Made with Cursor

[mossishahi]

Updated to also include the [[gnu::target_clones]] guard from #1367 by @angelobdev — this attribute is x86-specific and fails on ARM/Apple Silicon. Used #ifndef __APPLE__ to skip it on macOS.

This PR now covers the full set of changes needed:

• CMake: linker flags + OpenMP for Apple
• Vulkan: MoltenVK portability enumeration
• Compiler: guard x86-only target_clones on ARM

[nirmalpatelghub]

I didn't make in MAC OS. I am having Macbook Air M4.