Fix bug with stripping white space at the front of an option

After advancing the passed in pointer, the destination never
got set.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/parse.c b/parse.c
index 57865b1..bf1dea9 100644
--- a/parse.c
+++ b/parse.c
@@ -142,6 +142,8 @@
 
 	while (isspace(*s))
 		s++;
+
+	*p = s;
 }
 
 void strip_blank_end(char *p)