#9 librsync 0.9.7 as windows dll

[Sam Liddicott]

This patch declares rs_compare_targets as cdecl and removes the explicit callback typecast.
The typecast was not needed in unix (afaik) and didn't work in windows if cdecl was not specified and isn't needed if cdecl is specified

It adds a sources file suitable for MSVC build system, and a .def file to help build the dll.

The patch needs some review but allows me to build a DLL on windows. I'll now be testing the DLL

[Sam Liddicott]

Help build windows DLL using MSVC build.exe