Turn on -Wold-style-cast and fix the errors.

A couple of dodgy cases where we cast away const, but otherwise pretty boring.

Change-Id: Ibc39ebd525377792b5911464be842121c20f03b9
diff --git a/libc/stdio/local.h b/libc/stdio/local.h
index 7033eda..ce04141 100644
--- a/libc/stdio/local.h
+++ b/libc/stdio/local.h
@@ -124,6 +124,7 @@
 #define __sferror(p)   (((p)->_flags & __SERR) != 0)
 #define __sclearerr(p) ((void)((p)->_flags &= ~(__SERR|__SEOF)))
 #define __sfileno(p)   ((p)->_file)
+#if !defined(__cplusplus)
 #define __sgetc(p) (--(p)->_r < 0 ? __srget(p) : (int)(*(p)->_p++))
 static __inline int __sputc(int _c, FILE* _p) {
   if (--_p->_w >= 0 || (_p->_w >= _p->_lbfsize && (char)_c != '\n')) {
@@ -132,6 +133,7 @@
     return (__swbuf(_c, _p));
   }
 }
+#endif
 
 /* OpenBSD declares these in fvwrite.h but we want to ensure they're hidden. */
 struct __suio;