Fix qualified modifier lookup.

test/libsolidity/semanticTests/modifiers/access_through_module_name.sol

@@ -0,0 +1,25 @@
+==== Source: a ====
+import "a" as M;
+contract C {
+    uint public x;
+    modifier m { x = 1; _; }
+
+    function f() public M.M.C.m returns (uint t, uint r) {
+        t = x;
+        x = 3;
+        r = 9;
+    }
+    function g() public m returns (uint t, uint r) {
+        t = x;
+        x = 4;
+        r = 10;
+    }
+}
+// ----
+// x() -> 0x00
+// f() -> 1, 9
+// x() -> 3
+// g() -> 1, 0x0a
+// x() -> 4
+// f() -> 1, 9
+// x() -> 3