Updated: inkscape 0.92.3-2 (Test)

[Mark Geisert]

I've uploaded a non-maintainer re-build of the existing inkscape 0.92.3. 
This attempts to work around a problem with the current inkscape reported 
to exit with 127 error code (missing DLL entry).

This build was produced with gcc-g++ 7.4 while the current build was 
produced with gcc-g++ 6.4.  Newer gcc-g++ releases than these fail to 
build our existing inkscape due to C++ include file evolution.

The only changes in this test build were to the cygport file:
- inherit python3 rather than 'python'
- supply a BUILD_REQUIRES containing most if not all requirements

..mark