Windows builds: remove over-quotation of LIBZ macro

The LIBZ macro definition was already quoted in BASE_windows, then got
quotified once more in windows-makefile.tmpl.  That's a bit too much
quotations, ending up with the compiler being asked to define the
macro |"LIBZ=\"ZLIB1\""| (no, not the macro LIBZ with the value
"ZLIB1").  This is solved by removing the extra quoting in
BASE_windows.

Along with this, change the quotation of macro definitions and include
file specification, so we end up with things like -I"QuotedPath" and
-D"Macro=\"some weird value\"" rather than "-IQuotedPath" and
"-DMacro=\"some weird value\"".

Fixes #5827

Reviewed-by: Andy Polyakov <appro@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5833)