* python/libvir.c, python/libvir.py: Make Python aware that
	  the C bindings module is called cygvirtmod.dll when compiled
	  by CYGWIN.
	* python/Makefile.am: Remove symlink libvirtmod.dll -> cygvirtmod.dll
	  no longer necessary because of the above.
	* configure.in: Remove AM_CONDITIONAL(CYGWIN).