fix: ggml: fix vulkan-shaders-gen build (#10448)

* fix: ggml: fix vulkan-shaders-gen build

The vulkan-shaders-gen target was not being built correctly
in case of cross-compilation.
Other outputs need to be built for the cross compile target,
but vulkan-shaders-gen needs to be built for the host.

* refactor: ggml: Improve vulkan-shaders-gen toolchain setup

- Add GGML_SHADERS_GEN_TOOLCHAIN CMake option.
- Auto-detect host toolchain if not set.

* refactor: ggml: Improve vulkan-shaders-gen toolchain setup

Use configure_file to generate host_toolchain.cmake from template

* fix: ggml: Fix compile error

Fix compile error not finding vulkan-shaders-gen

* fix: vulkan-shaders-gen build and path handling

Fix build issues with vulkan-shaders-gen:
- Add target dependency for correct build order
- Use CMAKE_HOST_SYSTEM_NAME for executable suffix
- Fix MSVC output directory in host toolchain
- Normalize path handling for cross-compilation

* fix: improve host compiler detection in vulkan shader build

Improve host compiler detection for vulkan shader generation:
- Add NO_CMAKE_FIND_ROOT_PATH to all compiler searches
- Consolidate compiler detection logic
- Fix Windows-specific MSVC detection
- Ensure correct compiler search in cross-compilation

* refactor: Simplify CMake function for detecting host compiler

Simplified the CMake function to improve the process of detecting the host compiler.

* fix: Remove unnecessary Vulkan library linkage in CMakeLists.txt

Since `vulkan-shader-gen.cpp` only requires the `glslc` executable
and not the Vulkan headers or libraries, CMakeLists.txt needs to
be corrected.
(See: ecc93d0558)

* refactor: Rename host_toolchain.cmake.in

- Rename host_toolchain.cmake.in to cmake/host-toolchain.cmake.in

* refactor: GGML_VULKAN_SHADERS_GEN_TOOLCHAIN

Rename the macro GGML_SHADERS_GEN_TOOLCHAIN to GGML_VULKAN_SHADERS_GEN_TOOLCHAIN

ggml/CMakeLists.txt

@@ -185,6 +185,9 @@ option(GGML_OPENCL_PROFILING                "ggml: use OpenCL profiling (increas
 option(GGML_OPENCL_EMBED_KERNELS            "ggml: embed kernels"                             ON)
 option(GGML_OPENCL_USE_ADRENO_KERNELS       "ggml: use optimized kernels for Adreno"          ON)
 
+# toolchain for vulkan-shaders-gen
+set   (GGML_VULKAN_SHADERS_GEN_TOOLCHAIN "" CACHE FILEPATH "ggml: toolchain file for vulkan-shaders-gen")
+
 # extra artifacts
 option(GGML_BUILD_TESTS    "ggml: build tests"    ${GGML_STANDALONE})
 option(GGML_BUILD_EXAMPLES "ggml: build examples" ${GGML_STANDALONE})