Internals: Move array definitions to AstArrayDType instead of under AstVars.

Prep work for more complicated data types.

src/V3Depth.cpp

@@ -68,7 +68,7 @@ private:
 				   // Width, not widthMin, as we may be in middle of BITSEL expression which
 				   // though it's one bit wide, needs the mask in the upper bits.
 				   // (Someday we'll have a valid bitmask instead of widths....)
-				   AstVar::LogicPacked(), nodep->width());
+				   AstLogicPacked(), nodep->width());
 	if (!m_funcp) nodep->v3fatalSrc("Deep expression not under a function");
 	m_funcp->addInitsp(varp);
 	// Replace node tree with reference to var