Add --debugi-<srcfile> option.

src/V3Hashed.cpp

@@ -53,7 +53,11 @@ private:
     // STATE
     V3Hash		m_lowerHash;	// Hash of the statement we're building
 
-    //int debug() { return 9; }
+    static int debug() {
+	static int level = -1;
+	if (VL_UNLIKELY(level < 0)) level = v3Global.opt.debugSrcLevel(__FILE__);
+	return level;
+    }
 
     // METHODS
     void hashNodeIterate(AstNode* nodep) {