<Hermetic> Build Python2.7 statically using Soong.

1. Build Python2.7 statically (for sys libs, still dynamically get
linked) for Linux-x86-64 host.

2. Fixed a small build issue for _testcapi.

Modules/config.c is checked-in as source file. Ideally it can be
generated by parsing Android.bp file with some genrule.

Linux/pyconfig.h is for x86-64bit. For arm versioin, another pyconfig.h
will be checked-in under "Arm" dir.

Module: _ctypes is not contained within this patch. I am still trying to
figure out how the libffi works. Or we maybe use .swig directly.

For .py std libs, this static interpreter depends on /usr/lib/python2.7
for now.

Next step: pack up .py std libs, and bundle with this static
interpreter.

Test: cd out/host/linux-x86/bin/python2.7;./python -S
Bug: b/38395161

Change-Id: I680b120c1e056ff3589e8b4faa836bb204210437