Upgrade freetype to 2.6.3

[nthiery]

Motivation: on my Ubuntu box, upgraded recently to 16.04, compiling
freetype 2.6 fails due to a glitch in libtool (see log; similar to
libsndfile/libsndfile#132). The glitch disappears
with freetype 2.6.1, presumably thanks to an update of libtool.

Upgrading freetype to 2.6.1 in Sage should not hurt, and while we are
at it, we may as well upgrade to the latest version:

https://download.savannah.gnu.org/releases/freetype/freetype-2.6.3.tar.bz2

CC: @kiwifb @jdemeyer @vbraun

Component: packages: standard

Author: Nicolas M. Thiéry

Branch/Commit: 0268967

Reviewer: Volker Braun

Issue created by migration from https://trac.sagemath.org/ticket/20623

[nthiery]

Branch: u/nthiery/upgrade_freetype_to_2_6_3

[nthiery]

New commits:

0268967

20623: upgrade freetype standard package to 2.6.3

[nthiery]

Commit: 0268967

[nthiery]

comment:4

It's my first package upgrade; so I hope I did it right ...

[nthiery]

Compilation failure for freetype 2.6 on Ubuntu box upgraded to 16.04

[vbraun]

Reviewer: Volker Braun

[vbraun]

comment:5

Attachment: freetype-compile-failure.log

[vbraun]

Changed branch from u/nthiery/upgrade_freetype_to_2_6_3 to 0268967