libgnt/libgnt

Remove volatile from GntBindable registration.

2021-05-26, Elliott Sales de Andrade
81827d41b859
Remove volatile from GntBindable registration.

This causes a warning with GLib 2.67 and GCC 11.

Testing Done:
Compiled and saw no warnings.

Reviewed at https://reviews.imfreedom.org/r/674/
option('doc', type : 'boolean', value : true, yield : true,
description : 'build documentation with gtk-doc')
option('introspection', type : 'boolean', value : true, yield : true,
description : 'build introspection data')