Fix cairotwisted curve_length()
Avoid a crash when FT_Face is null

https://bugzilla.gnome.org/show_bug.cgi?id=724006
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.