cmake: Make sure to get the resource directory from the right clang compiler

The resource directory was always retrieved from the system's default clang
compiler instead of the targeted one.

Author: rherilier

CMakeLists.txt

@@ -132,9 +132,9 @@ endif()
 # Find Clang resource directory with Clang executable.
 
 if(NOT CLANG_RESOURCE_DIR)
-  find_program(CLANG_EXECUTABLE clang)
+  find_program(CLANG_EXECUTABLE clang-${Clang_VERSION_MAJOR})
   if(NOT CLANG_EXECUTABLE)
-    message(FATAL_ERROR "clang executable not found.")
+    message(FATAL_ERROR "clang-${Clang_VERSION_MAJOR} executable not found.")
   endif()
 
   execute_process(