Squash commits for public release

libs/libc/include/sys/cdefs.h

@@ -0,0 +1,23 @@
+#ifndef _LIBC_SYS_CDEFS_H
+#define _LIBC_SYS_CDEFS_H
+
+#if defined(__cplusplus)
+#define __BEGIN_DECLS extern "C" {
+#define __END_DECLS }
+#else
+#define __BEGIN_DECLS
+#define __END_DECLS
+#endif
+
+/* Define __use_instead macro for some functions so the user can be warned
+   about better/faster functions. */
+#ifndef __use_instead
+#ifdef __clang__
+#define __use_instead(F) __attribute__((diagnose_if(1, "use " F " instead", \
+    "warning")))
+#elif defined(__GNUC__)
+#define __use_instead(F) __attribute__((warning("use " F " instead")))
+#endif
+#endif
+
+#endif // _LIBC_SYS_CDEFS_H