mmap64: include stdint.h for uint64_t

Some targets include this implicitly, but pull it in explicitly for those
which don't to fix building for them.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

libc/sysdeps/linux/common/mmap64.c

@@ -10,6 +10,7 @@
 #ifdef __UCLIBC_HAS_LFS__
 
 #include <errno.h>
+#include <stdint.h>
 #include <unistd.h>
 #include <sys/mman.h>
 #include <sys/syscall.h>