Fix DEBUG=1 builds

Without this fix, I get the following error:

CC gccollect.c
gccollect.c: In function ‘gc_helper_get_regs’:
gccollect.c:63:1: error: bp cannot be used in asm here
windows: Complete rename of MICROPY_PATH_MAX to MICROPY_ALLOC_PATH_MAX (58ebde4)
Merge pull request #629 from dhylands/fix-unix-debug

Fix unix DEBUG=1 builds
Merge pull request #631 from stinos/fix-win-def

windows: Complete rename of MICROPY_PATH_MAX to MICROPY_ALLOC_PATH_MAX (...
Revert "Fix DEBUG=1 builds"

This reverts commit 6e76f7bc90fcd130db888f8804b8555dc8f3a484.

This patch tries to workaround a previous clang workaround. Instead of going
into workaround of workaround spiral, the original workaround should be tamed.
unix/gccollect.c: Make Clang workaround apply only to it. Unbreaks gcc builds.
py: Implement long int parsing in int(...).

Addresses issue #627.
py: Make int(<longint>) work by just returning the longint.