[ITP] libmspack 0.9

[Stuart Caie]

libmspack is a portable library for some loosely related Microsoft 
compression formats.

It is the library that powers cabextract. I'm the author of both and the 
current Cygwin maintainer of cabextract, but not libmspack.

With the most recent cabextract/libmspack releases, I prepared and 
uploaded new versions of both cabextract and libmspack, but only my 
cabextract release was accepted.

I wrote to the current maintaner, Yaakov Selkowitz, and he let me know I 
need to formally ITA libmspack. He gives his permission, pending review.

Yaakov has been using https://github.com/cygwinports/libmspack

I will be using 
https://github.com/kyz/libmspack/blob/master/libmspack/libmspack.cygport
- no patch needed, it's now in the main source
- no custom src_test() needed, libmspack now has a standard "make check" 
testsuite

Regards
Stuart