Looks like you have several problems. First of all, cygwin's gcc seems to be misinstalled. See what cygcheck -cv gcc says. Second, gcc isn't going to work with Activestate's perl, but if the perl that ran Makefile.PL was really Activestate, I don't think it would have tried to run cpp. I'm guessing that perl -V would show you are really running a cygwin perl (though you also have an Activestate perl installed).

As others have said, Activestate perl comes with Tk. To build Tk for cygwin perl, read the README.cygwin in the Tk distribution. I've heard reports that the native-windows flavor won't build under the newest (5.8.2 w/ithreads) perl; if this proves true, you might try getting an older cygwin perl (5.8.0 w/o ithreads), or build it for XFree86.