Fix handling of commas in arbitrary content in genexes.

As the comma is the parameter separator, it needs to be re-added
when evaluating to reconstruct arbitrary content.
Remove unused marker for a variable which is now used.
Remove unused typedef.
Remove unused vector population.

The call to GetEnabledLanguages does not have side-effects.
Merge topic 'unused-cleanup'

994dc70 Remove unused vector population.
44258cc Remove unused typedef.
0a4d7d8 Remove unused marker for a variable which is now used.
Merge topic 'fix-genex-comma-parse'

05bf972 Fix handling of commas in arbitrary content in genexes.
include_directories: Fix handling of empty or space-only entries

This is a regression introduced in commit 0d46e9a0 (Store includes
from the same include_directories call together., 2013-01-20).

Reported at

 http://thread.gmane.org/gmane.comp.programming.tools.cmake.user/46695/focus=7847
Merge topic 'fix-include_directories-whitespace-handling'

2f84dfe include_directories: Fix handling of empty or space-only entries