Fix broken rbash functionality when used as a login shell via /etc/passwd

http://bugs.gentoo.org/26854
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=170298

Backported from bash-3.1

--- bash-3.0/shell.c
+++ bash-3.0/shell.c
@@ -1089,6 +1099,8 @@
   if (restricted)
     return 1;
   temp = base_pathname (name);
+  if (*temp == '-')
+    temp++;
   return (STREQ (temp, RESTRICTED_SHELL_NAME));
 }