Update lldb for clang/llvm 3.4 import

This commit largely restores the lldb source to the upstream r196259
snapshot with the addition of threaded inferior support and a few bug
fixes.

Specific upstream lldb revisions restored include:

 SVN      git
181387  779e6ac
181703  7bef4e2
182099  b31044e
182650  f2dcf35
182683  0d91b80
183862  15c1774
183929  99447a6
184177  0b2934b
184948  4dc3761
184954  007e7bc
186990  eebd175

Sponsored by: DARPA, AFRL