Windows: Only set VERSION_QUAD if unset

When trying to build with some pretty typical version strings this was
causing failures trying to generate the windows resource file.

The resource file is already gated by an `ifdef` for this var, so
instead of blindly setting based on "VERSION", which can contain some
characters which are incompatible (e.g. 1.2.3.rc.0 will fail due to the
".rc").

Signed-off-by: Brian Goff <cpuguy83@gmail.com>
(cherry picked from commit ce931f28ea8768baa7ca2725d9030fbf8a40d3ba)
Signed-off-by: Brian Goff <cpuguy83@gmail.com>

hack/make/.go-autogen

@@ -58,7 +58,9 @@ if [ "$(go env GOOS)" = "windows" ]; then
 	fi
 
 	# Generate a Windows file version of the form major,minor,patch,build (with any part optional)
-	VERSION_QUAD=$(echo -n $VERSION | sed -re 's/^([0-9.]*).*$/\1/' | tr . ,)
+	if [ ! -v VERSION_QUAD ]; then
+		VERSION_QUAD=$(echo -n $VERSION | sed -re 's/^([0-9.]*).*$/\1/' | tr . ,)
+	fi
 
 	# Pass version and commit information into the resource compiler
 	defs=