hook-sysconfig _relpath based on hook-distutils

Prevents Makefile being added to datas twicely.

http://www.pyinstaller.org/ticket/783
verbose error message on assert is_package
Merge branch 'wooyek-feature/verbose_assert_is_package' into develop:

verbose error message on assert is_package
Merge pull request #145 from wooyek/feature/syconfig_hook_find_prefix

hook-sysconfig._relpath based on hook-distutils (which already contains such code)
pyi_crypto: Use modname instead of using a duplicated string
Merge pull request #147 from lvillani/pyi_crypto

pyi_crypto: Use modname instead of using a duplicated string