Fix --protect-ids when using SV classes (#2994)

A few names were incorrectly mangled, which made --protect-ids produce
invalid output when certain SV class constructs were uses. Now fixed and
added a few extra tests to catch this.

src/V3Task.cpp

@@ -1157,7 +1157,8 @@ private:
                 cfuncp->argTypes(EmitCBaseVisitor::symClassVar());
                 if (cfuncp->name() == "new") {
                     cfuncp->addInitsp(
-                        new AstCStmt(nodep->fileline(), "_ctor_var_reset(vlSymsp);\n"));
+                        new AstCStmt(nodep->fileline(),
+                                     VIdProtect::protect("_ctor_var_reset") + "(vlSymsp);\n"));
                 }
             }
         }