Unbreak build with gcc 4.3: provide missed includes and silence most annoying warnings.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47367 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Support/FileUtilities.cpp

@@ -16,6 +16,7 @@
 #include "llvm/System/Path.h"
 #include "llvm/System/MappedFile.h"
 #include "llvm/ADT/StringExtras.h"
+#include <cstdlib>
 #include <cstring>
 #include <cctype>
 using namespace llvm;