[klibc] [BUILTIN] Add support for ulimit -r

I recently found myself in need to have dash support 'ulimit -r' to
set maximum realtime priority. Attached is a patch that adds the
parameter to the builtin ulimit command and updates the manpage.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: maximilian attems <max@stro.at>
diff --git a/usr/dash/miscbltin.c b/usr/dash/miscbltin.c
index 8be613a..09282be 100644
--- a/usr/dash/miscbltin.c
+++ b/usr/dash/miscbltin.c
@@ -447,6 +447,9 @@
 #ifdef RLIMIT_LOCKS
 	{ "locks",			RLIMIT_LOCKS,	   1, 'w' },
 #endif
+#ifdef RLIMIT_RTPRIO
+	{ "rtprio",			RLIMIT_RTPRIO,	   1, 'r' },
+#endif
 	{ (char *) 0,			0,		   0,  '\0' }
 };