Fix failure to strip end of line with comment

We left a space at the end, which confused the postfix checking.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/parse.c b/parse.c
index f838a1f..d653f5e 100644
--- a/parse.c
+++ b/parse.c
@@ -152,7 +152,7 @@
 
 void strip_blank_end(char *p)
 {
-	char *s;
+	char *start = p, *s;
 
 	s = strchr(p, ';');
 	if (s)
@@ -164,7 +164,7 @@
 		p = s;
 
 	s = p + strlen(p);
-	while ((isspace(*s) || iscntrl(*s)) && (s > p))
+	while ((isspace(*s) || iscntrl(*s)) && (s > start))
 		s--;
 
 	*(s + 1) = '\0';