Added a test case that verifies that LLDB can debug across a process exec'ing itself into a new program. This currently is only enabled for Darwin since we exec from 64 bit to 32 bit and vice versa for 'x86_64' targets.

This can easily be adapted for linux and other platforms, but I didn't want to break any buildbots by assuming it will work.



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@182428 91177308-0d34-0410-b5e6-96231b3b80d8