CPython: Add explicit typecasts in _cffi_to_c_int()
Created originally on Bitbucket by dalcinl (Lisandro Dalcin)
Was already merged in Bitbucket before import, marked as merged by the import user
Source changeset not longer availableat the time of import. Commit listwill look empty
This is initial work to silent GCC -Wsign-compare. Running the testsuite with CFLAGS=-Wsign-compare currently fails, but that's related to how constants are handled, I'll try to provide a fix in an upcoming PR.