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

…ompiler

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

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(