Ensure <fcntl.h> defines the S_* constants from <sys/stat.h>.

POSIX says "The <fcntl.h> header shall define the symbolic constants for file
modes for use as values of mode_t as described in <sys/stat.h>".

Needed to build ToT strace.

Change-Id: Ia85a51ef6fd86a48084fe48ce24963000a937d37

libc/include/fcntl.h

@@ -33,6 +33,7 @@
 #include <sys/types.h>
 #include <linux/fadvise.h>
 #include <linux/fcntl.h>
+#include <linux/stat.h>
 #include <linux/uio.h>
 #include <unistd.h>  /* this is not required, but makes client code much happier */