[lldb] Don't swallow crashlog exceptions

crashlog.py catches every exception in order to format them. This
results in both the exception name as well as the backtrace getting
swallowed.

Here's an example of the current output:

  error: python exception: in method 'SBTarget_ResolveLoadAddress', argument 2 of type 'lldb::addr_t'

Compare this to the output without the custom exception handling:

  Traceback (most recent call last):
    File "[...]/site-packages/lldb/macosx/crashlog.py", line 929, in __call__
      SymbolicateCrashLogs(debugger, shlex.split(command))
    File "[...]/site-packages/lldb/macosx/crashlog.py", line 1239, in SymbolicateCrashLogs
      SymbolicateCrashLog(crash_log, options)
    File "[...]/site-packages/lldb/macosx/crashlog.py", line 1006, in SymbolicateCrashLog
      thread.dump_symbolicated(crash_log, options)
    File "[...]/site-packages/lldb/macosx/crashlog.py", line 124, in dump_symbolicated
      symbolicated_frame_addresses = crash_log.symbolicate(
    File "[...]/site-p...