Remove LLDB dependency on xcodeworkspace (on Linux) for version number

- make LLDB version number match Clang (and the Debian package)
- use the same revision detection magic that Clang uses to report SVN/Git revisions
- update test case as per above

Example output:

  $ lldb -v
  lldb version 3.3 (https://dmalea@llvm.org/svn/llvm-project/lldb/trunk revision 176211 clang revision 176208 llvm revision 176208)
ss

This line, and those below, will be ignored--

M    source/lldb.cpp
M    test/help/TestHelp.py
M    source/Makefile

llvm-svn: 176268