Cleanup TestUniqueTypes.py and add getCompilerVersion() to test harness
- pull up logic to get compiler version from TestUniqueTypes.py into lldbtest.py
- work around an GCC 4.6.3 issue



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@176190 91177308-0d34-0410-b5e6-96231b3b80d8