Makefile fix: when determining whether the suffix `.exe` should be used, test whether the OS is Windows, not whether the compiler is MSVC.

This should speed up installation slightly.

of menhir --suggest-ocamlfind, so that the Makefile works when
Menhir is compiled as a Windows executable. (Suggested by Jonathan
Protzenko.)

uninstall) to work regardless of whether we are in a distributed package or in
the repository.

Should fix the previous code, which was perhaps broken.

In the previous version, the redefinition of $(libdir) was ineffective when we were called from opam, which overrides $(libdir) from outside.

and installation to fail with "TARGET=byte". (Reported by Daniel Dickman.)

git-svn-id: svn+ssh://scm.gforge.inria.fr/svnroot/menhir@348 0f8b5475-4b4e-0410-85a8-ee3154a6bfe7

git-svn-id: svn+ssh://scm.gforge.inria.fr/svnroot/menhir@333 0f8b5475-4b4e-0410-85a8-ee3154a6bfe7

git-svn-id: svn+ssh://scm.gforge.inria.fr/svnroot/menhir@320 0f8b5475-4b4e-0410-85a8-ee3154a6bfe7