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/libcurl.dsw

@@ -0,0 +1,29 @@
+Microsoft Developer Studio Workspace File, Format Version 6.00
+# WARNING: DO NOT EDIT OR DELETE THIS WORKSPACE FILE!
+
+###############################################################################
+
+Project: "libcurl"=".\libcurl.dsp" - Package Owner=<4>
+
+Package=<5>
+{{{
+}}}
+
+Package=<4>
+{{{
+}}}
+
+###############################################################################
+
+Global:
+
+Package=<5>
+{{{
+}}}
+
+Package=<3>
+{{{
+}}}
+
+###############################################################################
+