New comment by natrys on void-packages repository

https://github.com/void-linux/void-packages/pull/20003#issuecomment-597142064

Comment:
@Piraty Regarding the first point, variables such as `$CFLAGS` or `$LDFLAGS` don't seem to exist yet by the time `$configure_args` is defined. So not sure how to do away with the `do_configure` block entirely.