Fix failure to find overload resolution when overrides are involved

test/libsolidity/syntaxTests/inheritance/override/no_matching_resolution.sol

@@ -0,0 +1,11 @@
+contract A {
+    function f() virtual internal {}
+}
+contract B is A {
+    function f() virtual override internal {}
+    function h() pure internal { f; }
+}
+contract C is B {
+    function f() override internal {}
+    function i() pure internal { f; }
+}