First cut of PowerPC(64) support in LLDB.

Summary:
This adds preliminary support for PowerPC/PowerPC64, for FreeBSD.  There are
some issues still:

 * Breakpoints don't work well on powerpc64.
 * Shared libraries don't yet get loaded for a 32-bit process on powerpc64 host.
 * Backtraces don't work.  This is due to PowerPC ABI using a backchain pointer
   in memory, instead of a dedicated frame pointer register for the backchain.
 * Breakpoints on functions without debug info may not work correctly for 32-bit
   powerpc.

Reviewers: emaste, tfiala, jingham, clayborg

Reviewed By: clayborg

Subscribers: emaste, lldb-commits

Differential Revision: http://reviews.llvm.org/D5988

llvm-svn: 220944
diff --git a/lldb/source/Target/Thread.cpp b/lldb/source/Target/Thread.cpp
index 50e6f66..f1beac69 100644
--- a/lldb/source/Target/Thread.cpp
+++ b/lldb/source/Target/Thread.cpp
@@ -2281,6 +2281,8 @@
             case llvm::Triple::aarch64:
             case llvm::Triple::thumb:
             case llvm::Triple::mips64:
+            case llvm::Triple::ppc64:
+            case llvm::Triple::ppc:
             case llvm::Triple::hexagon:
                 m_unwinder_ap.reset (new UnwindLLDB (*this));
                 break;