Merge pull request matplotlib#3262 from mdboom/min-freetype-version

BLD : reduces the minimum version of freetype

1.4.0 RC1: --ftversion vs --version freetype version

Author: tacaswell

setupext.py

@@ -942,7 +942,7 @@ def check(self):
 
         return self._check_for_pkg_config(
             'freetype2', 'ft2build.h',
-            min_version='2.4', version=version)
+            min_version='2.3', version=version)
 
     def version_from_header(self):
         version = 'Failed to identify version.'