configure.ac: make it work with VisualStudio Express and 64 bit compile

Because VS Express has no native 64Bit compiler but a 64 Bit cross-
compiler. The path resolution to detect binaries and libraries was
not suitable for the cross compiler. The added resolution is only
effective if no native compiler was found.

Change-Id: I8066cb04f94eb4bfd0c57b35e5e39883c51ee046
Reviewed-on: https://gerrit.libreoffice.org/13515
Reviewed-by: David Ostrovsky <david@ostrovsky.org>
Tested-by: David Ostrovsky <david@ostrovsky.org>