/usr/bin/x86_64-linux-gnu-python-config is in libpython-dev 2.7.15~rc1-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/bin/x86_64-linux-gnu-python2.7-config
/usr/bin/x86_64-linux-gnu-python2.7-config