GPUDevice: Swap out glslang for shaderc

CMakeModules/DuckStationDependencies.cmake

@@ -16,6 +16,11 @@ if(NOT WIN32 AND NOT ANDROID)
   find_package(JPEG REQUIRED) # No version because flatpak uses libjpeg-turbo.
   find_package(CURL REQUIRED)
   find_package(Freetype 2.13.1 REQUIRED)
+
+  if(ENABLE_VULKAN OR APPLE)
+    find_package(Shaderc REQUIRED)
+  endif()
+
   if(APPLE)
     set(CMAKE_FIND_FRAMEWORK ${FIND_FRAMEWORK_BACKUP})
   endif()

CMakeModules/FindShaderc.cmake

@@ -0,0 +1,32 @@
+# - Try to find SHADERC
+# Once done this will define
+#  SHADERC_FOUND - System has SHADERC
+#  SHADERC_INCLUDE_DIRS - The SHADERC include directories
+#  SHADERC_LIBRARIES - The libraries needed to use SHADERC
+
+FIND_PATH(
+    SHADERC_INCLUDE_DIR shaderc/shaderc.h
+    HINTS /usr/include /usr/local/include
+    ${SHADERC_PATH_INCLUDES}
+)
+
+FIND_LIBRARY(
+    SHADERC_LIBRARY
+    NAMES shaderc_shared
+    PATHS ${ADDITIONAL_LIBRARY_PATHS} ${SHADERC_PATH_LIB}
+)
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(Shaderc DEFAULT_MSG
+                                  SHADERC_LIBRARY SHADERC_INCLUDE_DIR)
+
+if(SHADERC_FOUND)
+    add_library(Shaderc::shaderc_shared UNKNOWN IMPORTED)
+    set_target_properties(Shaderc::shaderc_shared PROPERTIES
+        IMPORTED_LOCATION ${SHADERC_LIBRARY}
+        INTERFACE_INCLUDE_DIRECTORIES ${SHADERC_INCLUDE_DIR}
+        INTERFACE_COMPILE_DEFINITIONS "SHADERC_SHAREDLIB"
+    )
+endif()
+
+mark_as_advanced(SHADERC_INCLUDE_DIR SHADERC_LIBRARY)