Fix import directive visits in type checker and view pure checker.

test/libsolidity/semanticTests/multiSource/import_overloaded_function.sol

@@ -0,0 +1,15 @@
+==== Source: A ====
+function sub(uint256 x, uint256 y) pure returns (uint) { return 1; }
+function sub(uint256 x) pure returns (uint) { return 2; }
+==== Source: B ====
+import {sub} from "A";
+contract C
+{
+    function f() public pure returns (uint, uint) {
+        return (sub(1, 2), sub(2));
+    }
+}
+// ====
+// compileViaYul: also
+// ----
+// f() -> 1, 2