libgnt/libgnt

Make all destroy functions multi-call safe.

2020-09-27, Elliott Sales de Andrade
ffb6069167a2
Make all destroy functions multi-call safe.

Also, fix an incorrect name for a dispose vfunc.

Testing Done:
Compile only, and the test from LIBGNT-11.

Reviewed at https://reviews.imfreedom.org/r/141/
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')