gplugin/gplugin

5b02e2cd29e2
Add a bunch of crap about how to get lgi installed on macos

Testing Done:
I copied the stuff I typed manually, so it should be good?

Reviewed at https://reviews.imfreedom.org/r/313/
gplugin_query = executable('gplugin-query',
'gplugin-query.c',
dependencies : [gplugin_dep, GLIB, GOBJECT],
install : get_option('install-gplugin-query'))
if get_option('help2man')
custom_target('gplugin-query.1',
command : [help2man,
'--name=Query installed plugins', '--section=1',
'--help-option=--help-all', '--no-info',
'--output', '@OUTPUT@',
gplugin_query],
output : 'gplugin-query.1',
install : get_option('install-gplugin-query'),
install_dir : get_option('mandir') / 'man1')
endif