[glib] genmarshal: Use fewer magic numbers

[Emmanuele Bassi <ebassi src gnome org>]

commit 616cff7c8700c70f6fcc50001cb6889ec181df10
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Wed Apr 26 13:48:36 2017 +0100

    genmarshal: Use fewer magic numbers
    
    https://bugzilla.gnome.org/show_bug.cgi?id=781755

 gobject/glib-genmarshal.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/gobject/glib-genmarshal.c b/gobject/glib-genmarshal.c
index f64b80c..a8ade38 100644
--- a/gobject/glib-genmarshal.c
+++ b/gobject/glib-genmarshal.c
@@ -1020,7 +1020,7 @@ parse_args (gint    *argc_p,
       else if ((strcmp ("--prefix", argv[i]) == 0) ||
               (strncmp ("--prefix=", argv[i], 9) == 0))
        {
-          gchar *equal = argv[i] + 8;
+          gchar *equal = argv[i] + strlen ("--prefix");
 
          if (*equal == '=')
            marshaller_prefix = equal + 1;
@@ -1035,7 +1035,7 @@ parse_args (gint    *argc_p,
       else if ((strcmp ("--output", argv[i]) == 0) ||
               (strncmp ("--output=", argv[i], 9) == 0))
        {
-          gchar *equal = argv[i] + 8;
+          gchar *equal = argv[i] + strlen ("--output");
 
          if (*equal == '=')
            output_fn = equal + 1;