Cygwin: Teach mklib/minstall to properly install libraries on cygwin

Cygwin: Teach mklib/minstall to properly install libraries on cygwin

Teach mklib/minstall more about cygwin so libraries are properly installed

Have mklib install the .dll into the lib/ staging directory as well

Have minstall install the .dll into PREFIX/bin at the same time as
installing the .dll.a link library into PREFIX/lib

mklib uses a '-' rather than a '.' as the separator before the version
number in library names on cygwin.  Change the install globs so they match
library names like that.

Signed-off-by: Jon TURNEY <jon.turney@dronecode.org.uk>
Signed-off-by: Brian Paul <brianp@vmware.com>