Configure.in tweaking for windows

[Tor Lillqvist]

> Sure, but why do you check for atls.lib file ?

Sorry, can't remember.

> CL_X64 is enough for the purpose, isn't it ?

"CL_X64" being non-empty means we are building a 64-bit LibreOffice.
(Yeah, hard to deduce from its name, feel free to change it. I blame
jcorrius, who first did work on a 64-bit build, and I think was the
one who introduced this variable name;) )  Note that the check we are
looking at:

        if test "$CL_X64" = "" -a -f
"$with_cl_home/atlmfc/lib/amd64/atls.lib"; then

tests that CL_X64 is *empty*. I.e. when building whole of LO as
64-bit, the "Prefer native x64 compiler to cross-compiler" checks are
not done. Whether that makes sense or not, no idea. I would really
like to be able to wash my hands from all this Windows crap.

Also note that "BUILD_X64" which is set here does not mean "build a
64-bit LO" as one might perhaps guess from its name, but "build 64-bit
Explorer extension", and/or maybe "build a 64-bit ActiveX component".

Yeah, CL_X64 and BUILD_X64 should be renamed to says more clearly what
their meaning is...

> Explorer extension is not an ActiveX, is it ?

atls.lib is not related to ActiveX, is it? It's the "Active Template
Library". So why does the AC_MSG_CHECKING here talk about "64bit
ActiveX component"? Is that a copy/paste error? Is this part of
configure.in related to the Explorer extension at all? The "ActiveX
component" is a completely different thing, isn't it? Bu then the
AC_MSG_WARN below says "Installation set will not contain the 64-bit
Explorer extension", yay. Makes no sense.

I guess my final words are: Feel free to change all this however you
like (and hopefully test that it works as intended in all supported
configurations, which we probably have too many of, each configuration
option doubles the space of combinations), as long as nobody expects
me to fix it all up afterwards, but note that I also don't claim to
understand what it does and what it is intended to do currently
either. Life is hard.

--tml