comma_scan()'s clean option wasn't removing entry at end of list.

lib/getmountlist.c

diff --git a/lib/getmountlist.c b/lib/getmountlist.c
index 332852a..f7d58ab 100644
--- a/lib/getmountlist.c
+++ b/lib/getmountlist.c
@@ -97,7 +97,10 @@
     no = 2*(*s == 'n' && s[1] == 'o');
     if (optlen == len-no && !strncmp(opt, s+no, optlen)) {
       got = !no;
-      if (clean && optlist) memmove(s, optlist, strlen(optlist)+1);
+      if (clean) {
+        if (optlist) memmove(s, optlist, strlen(optlist)+1);
+        else *s = 0;
+      }
     }
   }