ggml-vulkan/CMakeLists: add a check for SPIRV-Headers

This is installed by the project if it is built and installed.
Receiving an error during the configuration step is generally
preferred to receiving an error in the middle of a build.

Author: jeeb

ggml/src/ggml-vulkan/CMakeLists.txt

@@ -8,6 +8,8 @@ endif()
 
 find_package(Vulkan COMPONENTS glslc REQUIRED)
 
+find_package(SPIRV-Headers REQUIRED)
+
 if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
     # Parallel build object files
     add_definitions(/MP)