Detecting the need for -mwin32 in newer cygwin gcc's

[Christopher Faylor]

We've made a change in the newest version of cygwin that stops the
Windows headers from being searched unless a -mwin32 option is specified
on the gcc command line.  This option also causes Windows options like
"WIN32" to be defined automatically.

We've done this to make porting easier for some programs which already
have a Windows-specific port that is not appropriate when compiled under
Cygwin.

However, this causes problems for programs that still need to explicitly
use Windows include files.

Someone on the cygwin mailing list suggested that this calls for an
autoconf option so that checking for this behavior can be added to
configure.

Basically, I think we need something like a AC_PROG_GCC_USES_MWIN32.

Does this sound like a good way to go with this?

Does anyone want to volunteer to implement this, if so?

cgf