Add the necessary dependency for the Windows VC6 build to ensure 'pythoncore'

is built before '_ctypes' is attempted.
Will backport to 2.5 once it is unfrozen for 2.5.1.

PC/VC6/pcbuild.dsw

@@ -26,6 +26,9 @@ Package=<5>
 
 Package=<4>
 {{{
+    Begin Project Dependency
+    Project_Dep_Name pythoncore
+    End Project Dependency
 }}}
 
 ###############################################################################