Do not report missing stdc++fs on apple/clang (avast#1002)

macOS/clang never had the stdc++fs library that is required on some
systems using gcc. The message is therefore confusing when it
appears on a macos device and may be misleading when solving
for a compilation error.

This commit removes the message on macOS builds.

src/utils/CMakeLists.txt

@@ -53,7 +53,7 @@ elseif(UNIX AND (NOT APPLE) AND CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
 			stdc++fs
 	)
 # Library not found -> hope compiler does not need it.
-else()
+elseif(NOT APPLE)
 	message(STATUS "-- Library stdc++fs NOT found -> linking utils without stdc++fs library")
 endif()