glib-mkenums: require at least one input fileglib-mkenums-args-order

Previously, the behaviour if you supplied no input files was to crash:

    Traceback (most recent call last):
      File "/usr/bin/glib-mkenums", line 420, in <module>
        base = os.path.basename(options.args[0])
    IndexError: list index out of range

While in theory you might want to supply no input files, it is much more
likely to be a misconfiguration of the build process. Since this has
never worked, let's make that explicit:

    glib-mkenums: error: the following arguments are required: args

1 files changed, 1 insertions, 1 deletions

diff --git a/gobject/glib-mkenums.in b/gobject/glib-mkenums.in
index 1d2052ce7..07b1d3e0a 100755
--- a/gobject/glib-mkenums.in
+++ b/gobject/glib-mkenums.in
@@ -325,7 +325,7 @@ parser.add_argument('--template', default='', dest='template',
 parser.add_argument('--output', default=None, dest='output')
 parser.add_argument('--version', '-v', default=False, action='store_true', dest='version',
                     help='Print version informations')
-parser.add_argument('args', nargs='*')
+parser.add_argument('args', nargs='+')
 
 options = parser.parse_args()