Test for -ffile-prefix-map support instead of comparing versions.

Comparing versions is not viable because Apple clang has its own
versioning scheme which is also undocumented.

CMakeLists.txt

@@ -66,12 +66,13 @@ endif()
 
 # common compiler flags
 
-if((CMAKE_CXX_COMPILER_ID STREQUAL "GNU" AND NOT (CMAKE_CXX_COMPILER_VERSION VERSION_LESS 8.0)) OR
-        CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-    set(DEBUG_FLAGS "-fdebug-prefix-map=${CMAKE_CURRENT_SOURCE_DIR}=.")
-    set(DEBUG_FLAGS "${DEBUG_FLAGS} -ffile-prefix-map=${CMAKE_CURRENT_SOURCE_DIR}=.")
-    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${DEBUG_FLAGS}")
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${DEBUG_FLAGS}")
+include(CheckCXXCompilerFlag)
+
+set(FILE_PREFIX_MAP "-ffile-prefix-map=${CMAKE_CURRENT_SOURCE_DIR}=.")
+check_cxx_compiler_flag("${FILE_PREFIX_MAP}" HAS_FILE_PREFIX_MAP)
+if(HAS_FILE_PREFIX_MAP)
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${FILE_PREFIX_MAP}")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${FILE_PREFIX_MAP}")
 endif()
 
 if(MINGW)