build: add libcrypt32 dep for new mingw. Also ensure that libgcc/libstdc++ are static-linked regardless of the toolchain config
Upgrade gitian win32 to Precise 12.04.

mingw upgrade allows more hardening, compiler bug fixes and possibily win64 later.
Rename deps .zip files to be more consistent in revision format.
Boost #4258 build fix for mingw32
Upgrade gitian win32 to boost-1.54.0

Workaround 1.54.0 build bug, upstream #9156
Workaround 1.51.0+ human bug, upstream #7262

This commit also demonstrates a method to verify the integrity of inputs.
Merge pull request #3029 from wtogami/gitianwin32

Upgrade gitian win32 to Precise 12.04.