Fix handling of format strings to work with python 2.6

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@216314 91177308-0d34-0410-b5e6-96231b3b80d8
stuff
Merge branch 'master' of http://llvm.org/git/libcxx
Merge branch 'master' into lit-abi
stuff
[libcxx] Add --show-unsupported and --show-xfail to check-libcxx's default LIT args.

Summary:
In order to gather more information about testsuite results these flags should be added to LIT's default args.
These new switches were recently added to LIT. It been more than two weeks since both switches were added.
I think its time we add these to our LIT flags.


Reviewers: mclow.lists, danalbert

Reviewed By: danalbert

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D5037

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@216315 91177308-0d34-0410-b5e6-96231b3b80d8
Merge branch 'master' of http://llvm.org/git/libcxx
Merge branch 'master' into lit-abi