libgnt/libgnt

fix typo to check for correct instance type

2021-07-15, ivanhoe
f0b34eb0e27d
fix typo to check for correct instance type

Testing Done:
None besides running `ninja`. This is RR 793 for the default branch. See notes there. There seems to be no Sounds menu in Finch3 anymore.

Reviewed at https://reviews.imfreedom.org/r/813/
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')