Add option to select the OpenSUSE Mirror and fix package versions in 'make win-extras'

There are new versions of libexpat in opensuse mirrors. Also, it seems that mingw{32,64}-libexpat-* is noew mingw{32,64}-libexpat1-*.

Additionally, I added an option to Make.inc (OPENSUSE_MIRROR) to make easier to select the desire openSUSE mirror until #7628 is fixed.