Remove std:: prefixes from C functions in talk/.

std::memcpy -> memcpy for instance. This change was motivated by a
compile report complaining that std::rand() was used instead of rand(),
probably with a stdlib.h include instead of cstdlib. Use of C functions
without the std:: prefix is a lot more common, so removing std:: to
address this.

BUG=
R=tommi@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/9559004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@5657 4adac7df-926f-26a2-2b94-8c16560cd09d

talk/base/stringutils.h

@@ -31,6 +31,7 @@
 #include <ctype.h>
 #include <stdarg.h>
 #include <stdio.h>
+#include <string.h>
 
 #ifdef WIN32
 #include <malloc.h>
@@ -46,7 +47,6 @@
 #endif  // !BSD
 #endif  // POSIX
 
-#include <cstring>
 #include <string>
 
 #include "talk/base/basictypes.h"