build: Added Visual Studio 6.0 (VC6) project files

Carrying on from commit 11025613b9 added a more thorough version of
the VC6 project files which are capable of supporting side-by-side
compilation, as well as support for some of the third-party libraries
curl uses.

projects/Windows/VC6/lib/.gitignore

@@ -0,0 +1,4 @@
+/*.dsp
+/*.html
+/*.ncb
+/*.opt