Tomasz Miąsko authored Feb 15, 2018 and Christoph Reiter committed Jul 28, 2018

Functional changes:

* Consistently check that return code from pkg-config is zero.
* Use shell word splitting rules to process pkg-config output to match
  behaviour obtained by running `cc program.cc $(pkg-config --cflags ...)`.
  Fixes issue #171 .
* Use user preferred encoding to process output from pkg-config on
  Python 3. Python 2 behaviour defaults to using ascii encoding as before.

edit creiter: still ignore pkg-config errors by default for now as we
depend on it when glib is a subproject.