look-ma-no-sources.ebuild: Drop call to non-existent distutils-r1_pkg_postinst

Signed-off-by: Gregory M. Tuner <gmt@be-evil.net>
look-ma-no-sources.ebuild: convert to single-python-abi distutils-r1 usage

Signed-off-by: Gregory M. Tuner <gmt@be-evil.net>