ccache gcc work-around

CMake/cotire.cmake

@@ -1863,13 +1863,12 @@ function (cotire_precompile_prefix_header _prefixFile _pchFile _hostFile)
 	if (_option_COMPILER_ID MATCHES "MSVC")
 		# cl.exe messes with the output streams unless the environment variable VS_UNICODE_OUTPUT is cleared
 		unset (ENV{VS_UNICODE_OUTPUT})
-	elseif (_option_COMPILER_ID MATCHES "Clang")
+	elseif (_option_COMPILER_ID MATCHES "GNU|Clang")
 		if (_option_COMPILER_LAUNCHER MATCHES "ccache" OR
 			_option_COMPILER_EXECUTABLE MATCHES "ccache")
-			# Clang seems to embed a compilation timestamp into the precompiled header binary,
-			# which results in "file has been modified since the precompiled header was built"
-			# errors if ccache is used. We work around the problem by disabling ccache upon
-			# pre-compiling the prefix header.
+			# Newer versions of Clang and GCC seem to embed a compilation timestamp into the precompiled header binary,
+			# which results in "file has been modified since the precompiled header was built" errors if ccache is used.
+			# We work around the problem by disabling ccache upon pre-compiling the prefix header.
 			set (ENV{CCACHE_DISABLE} "true")
 		endif()
 	endif()