gplugin/gplugin

Remove volatile from variable for g_once_init_*.

2021-05-26, Elliott Sales de Andrade
62405791d543
Remove volatile from variable for g_once_init_*.

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/672/
if get_option('rs')
add_languages('rust')
subdir('tests')
endif # rs