build/Makefile-msvcproj.am: Remove Generated Intermediate Files

Delete libpangocairo.vs10.sourcefiles and
libpangocairo.vs10.sourcefiles.filters once we are done with them, so to
fix make distcheck
MSVC Builds: Update Introspection Build Process

GObject-Introspection was recently changed to support acquiring the name of
the DLL from a library (.lib, etc) that was passed into g-ir-scanner on
Windows, like the *nix builds, instead of directly passing in the name of
the DLL.

This updates the introspection build process, so that introspection files
for Pango can continue to be properly built.
Merge branch 'master' of git://git.gnome.org/pango