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

tools/llvmc/llvmc.cpp

@@ -21,6 +21,7 @@
 #include "llvm/Support/ManagedStatic.h"
 #include "llvm/System/Signals.h"
 #include <iostream>
+#include <cstring>
 using namespace llvm;
 
 //===----------------------------------------------------------------------===//