have Win32CORE use ALIAS/XSANY

have Win32CORE use ALIAS/XSANY

Using XSANY in addition to a struct of strings, saved 650 bytes (.rdata
and .text combined, 32bit/MS VC2K3/O1) from the previous implementation of
Win32CORE. Instead of encoding pointers or relative pointer sized offsets
to string literals, use unsigned chars. Instead of creating new XSUB C
function stubs, one per forwarded sub, use the ALIAS/XSANY feature and
have only 1 XSUB which has many names. If a length aware version of newXS
is ever added to perl, the sub names's lengths already are available. See
also commit eff5b9d539e for something similar to this commit.