Add $(Windows), which is "YES" if the host platform is a Windows
platform (mingw32 or cygwin32), and "NO" otherwise.
# Pin a suffix on executables? If so, what (Windows only).
exeext=@exeext@
+# Windows=YES if on a Windows platform
+ifneq "$(findstring $(HostOS_CPP), mingw32 cygwin32)" ""
+Windows=YES
+else
+Windows=NO
+endif
+
################################################################################
#
# project-wide flags