[PATCH] [libcxx] Use pseudo-terminal in LIT tests so color output from compiler error messages is captured.

[Daniel Dunbar]

But what if Lit isn't running in a device capable of color output? Won't
this add a bunch of ugly ASCII codes?

I think what tools like Ninja do is to also optionally strip the color
codes in that case (
https://github.com/martine/ninja/blob/master/src/util.cc#L384).

 - Daniel

http://reviews.llvm.org/D6010