Fix build failures with python support on sparc-solaris

Fix build failures with python support on sparc-solaris

There were two types of errors, mostly compiler warnings:

  1. _FILE_OFFSET_BITS being redefined in pyconfig.h;
     This is a problem we're familiar with, having seen similar
     issues on GNU/Linux systems. I used a similar solution.

  2. GCC 4.5 complains that calls to PyEval_InitThreads and
     PyEval_ReleaseLock have no effect.  This is because our Python
     is built without thread support, leading us to use the dummy
     #define in python-internal.h which just gets replaced by `0'.
     Since this function returns void (checked versions 2.4 and 2.7),
     I simply removed the 0.

gdb/ChangeLog:

        python/python-internal.h (_FILE_OFFSET_BITS): Undefine.
        (PyEval_InitThreads): Remove duplicate. Define as nothing.
        (PyEval_ReleaseLock): Define as nothing.