Add gdb pretty printers for a wide variety of libc++ data structures (take 2).

This patch is an exact duplicate of, except
that it uses the newly introduced testing framework to detect if gdb is present
so that the tests won't fail on machines without gdb.

Reviewers: echristo, EricWF

Subscribers: christof, ldionne, llvm-commits

Tags: #llvm

Differential Revision:

git-svn-id: 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed