Remove redundant macros from win32 makefiles

Remove redundant macros from win32 makefiles

In the course of removing redundant ByteLoader references I found that
various long lists of extensions are hopelessly out of date, e.g.
Compress/Zlib should be Compress/Raw/Zlib and PerlIO/*, threads/* and
others are missing. It seems that these lists of extensions serve no
useful purpose anyway: in Makefile they are used to delete files that
should already have been deleted by the Makefile for each module, and
in makefile.mk DYNAMIC_EXT wasn't used at all! So the simplest remedy
is to remove them. One less maintenance headache.

p4raw-id: //depot/perl@29376