Put back inline definitions if using an old API.

All these inlines were turned in to out of line definitions in L.
This brings us a step closer to being able to just use the current
bionic headers for the NDK, rather than having many old versions of
them.

Change-Id: Ie010bc727d78d3742abc577c70f6578db2e68625

libc/include/sys/stat.h

@@ -171,7 +171,7 @@ mode_t umask(mode_t mode) {
 }
 #endif /* defined(__BIONIC_FORTIFY) */
 
-extern int mkfifo(const char*, mode_t);
+_BIONIC_NOT_BEFORE_21(extern int mkfifo(const char*, mode_t);)
 extern int mkfifoat(int, const char*, mode_t);
 
 extern int fchmodat(int, const char*, mode_t, int);
@@ -183,6 +183,10 @@ extern int mknodat(int, const char*, mode_t, dev_t);
 extern int utimensat(int fd, const char *path, const struct timespec times[2], int flags);
 extern int futimens(int fd, const struct timespec times[2]);
 
+#if __ANDROID_API__ < 21
+#include <android/legacy_sys_stat_inlines.h>
+#endif
+
 __END_DECLS
 
 #endif /* _SYS_STAT_H_ */