Remove a gcc-4.5 compilation warning:
bionic/libc/include/../include/stdlib.h: In function 'int grantpt(int)':
bionic/libc/include/../include/stdlib.h:138:23: warning: parameter '__fd' set but not used [-Wunused-but-set-parameter]

By adding __attribute((unused)) to __fd, the warning is gone, and this
attribute is compatible with gcc-4.4.0, gcc-4.3.1 gcc-4.2.1.
There is no any side effect.

Change-Id: Id9d2b0aeefdd9c37132da0f00c48387f7d897e83
diff --git a/libc/include/stdlib.h b/libc/include/stdlib.h
index 41e8d26..5a991ac 100644
--- a/libc/include/stdlib.h
+++ b/libc/include/stdlib.h
@@ -135,7 +135,7 @@
 extern int    ptsname_r(int, char*, size_t);
 extern int    getpt(void);
-static __inline__ int grantpt(int __fd)
+static __inline__ int grantpt(int __fd __attribute((unused)))
   return 0;     /* devpts does this all for us! */