Hash improvement for complex, str and long.

[Daetalus]

Change

• Pypy parser could not handle complex literal correctly, it always treat complex as 0.0j. Fix it. The code originally write by Marius.
• Add hash function to complex. Already tested. (But did not enable test_hash, please see below)
• Fix the wrong mpz usage in long constructor.
• Treat the hash value of empty string as Zero, like CPython did.

Note
After read CPython code. CPython str hash function will check PYTHONHASHSEED enviroment varialble in random.c file. But the Pyston DJB based str hash function didn't support it. I did some experiments try to fix it. But seems I couldn't use random number in str hash function (types.h). Pyston will report error:

pyston: ../../src/runtime/builtin_modules/thread.cpp:189: void pyston::setupThread():
Assertion `thread_module' failed.

[kmod]

these should be throwCapiException() -- returning -1 is the capi way for hash functions to specify that they threw an exception.

[kmod]

awesome thanks :)