Improve error message when freetype headers are not found using python3

[jenshnielsen]

Make it possible to disable the pgk-config version check even when a version is not known and use this with freetype.

This avoids trying to compare numbers to a string when the freetype version
cound not be found from headers or freetype-config. pgk-config is useless
for detecting the freetype version since it returns the libtool version and not the freetype version.

The result when freetype is not found is now (both python 2 and 3)

freetype: no  [The C/C++ header for freetype2 (ft2build.h)
                        could not be found.  You may need to install the
                        development package.]

There is still scope for some larger improvements in the setupext.py code but these are the minimum changes needed to fix the issue reported at the mailing list here http://matplotlib.1069221.n5.nabble.com/matplotlib-devel-1-4-3-does-not-build-on-Ubuntu-14-with-python3-td45301.html

We might want to backport this to color_overhaul

[tacaswell]

👍 On backporting.

[montefra]

for the records: both on (k)ubuntu 14.10 and opensuse tumbleweeds I had to install
development packages of freetype and libXft to get rid of the nasty error message and be able to install matplotlib. Might be worth to point out also about the second dependency, to avoid other bug reports.

souce

[jenshnielsen]

In my testing I can't see any sign that libxft-dev is a dependency needed here. It is a dependency of some of the gui backends but that is a different issue and should be correctly handled by the apt-get

I.e. the following works for me without any issues:

sudo apt-get remove libxft-dev
python setup.py build

Can you be a bit more specific about which error message you see with freetype dev headers installed and not libxft-dev?

[mdboom]

👍

[montefra]

Sorry about the noise.

The problem is that on opensuse there is a freetype-devel and freetype2-devel and I need the latter to build matplotlib. It is installed by libxft-devel.
Now I switch to my kubuntu os and I check there too.

Edit:

on kubuntu I could install matplotlib after removing libxft-dev. I thought I remembered having freetype dev installed and not being able to install matplotlib, but I'm probably just getting old :)

[jenshnielsen]

@montefra Thanks for clearing that up. The freetype vs freetype2 situation is a bit confusing. I don't quite know what we can do about that other than mention it somewhere in the docs.

[tacaswell]

Backported as f918227

@jenshnielsen Thank you.