Issue #13756: Fix building extensions modules on Cygwin

Patch by Roumen Petrov, based on original patch by Jason Tishler.
diff --git a/Modules/makesetup b/Modules/makesetup
index 3297b78..b872337 100755
--- a/Modules/makesetup
+++ b/Modules/makesetup
@@ -91,7 +91,7 @@
 	 else
 	 	ExtraLibDir='$(LIBPL)'
 	 fi
-	 ExtraLibs="-L$ExtraLibDir -lpython\$(VERSION)";;
+	 ExtraLibs="-L$ExtraLibDir -lpython\$(LDVERSION)";;
 esac
 
 # Main loop