Since Renata's ERRATA was unclear to whether or not this was *actually* removed (please point to a changeset if the option was removed):
If the option is no longer required by Pidgin and that was the original reason to have it in the first, there's really no reason *not* to remove this, no?

Eg this code
> int main() { return 0; }
Fails to compile on MingW gcc 4.6 and 4.7 when passing -mno-cygwin to gcc. The solution that distutils does not work with current versions of MingW (and GCC) for good is unacceptable so the only working solution is removal of no-cygwin. Just that GCC 4.4 would support the flag does not change this bug one way or the other.