perf clang: Fix build with Clang 9

LLVM D59377 (included in Clang 9) refactored Clang VFS construction a
bit, which broke perf clang build. Let's fix it.

Signed-off-by: Maciej S. Szmigiero <[e-mail]>
Reviewed-by: Dennis Schridde <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: [e-mail]
Cc: Denis Pronin <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Naohiro Aota <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: http://lore.kernel.org/lkml/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/c++/clang.cpp

···
 	CompilerInstance Clang;
 	Clang.createDiagnostics();
 
+#if CLANG_VERSION_MAJOR < 9
 	Clang.setVirtualFileSystem(&*VFS);
+#else
+	Clang.createFileManager(&*VFS);
+#endif
 
 #if CLANG_VERSION_MAJOR < 4
 	IntrusiveRefCntPtr<CompilerInvocation> CI =