Correctly determine whether base constructor is called without parentheses.

test/libsolidity/syntaxTests/inheritance/modifiers_in_constructor_context.sol

@@ -0,0 +1,9 @@
+// This generated an invalid warning on m1 in some compiler versions.
+contract A {
+  constructor() m1 public { }
+  modifier m1 { _; }
+}
+contract B is A {
+  modifier m2 { _; }
+  constructor() A() m1 m2 public {  }
+}