gst: Don't intercept --help in gst_init()

gst: Don't intercept --help in gst_init()

Before this patch gst_init would intercept --help, causing for example
cheese's --help to look like this:

[hans@shalem cheese]$ cheese --help
Usage:
  cheese [OPTION...] - GStreamer initialization

Help Options:
  -h, --help                        Show help options
  --help-all                        Show all help options
  --help-gst                        Show GStreamer Options

gst_init is the only gfoo_init function which does this.

https://bugzilla.gnome.org/show_bug.cgi?id=702089