Move test to /closures folder, add new test for non-cap closure <-> FnPtr checking.

Author: ldm0

src/test/ui/issues/issue-46742-1.rs renamed to src/test/ui/closures/issue-46742-1.rs

@@ -0,0 +1,19 @@
+// check-pass
+fn foo(x: i32) -> i32 {
+    x
+}
+fn main() {
+    // We still can coerce non-capturing closure to function pointer
+    let _ = if true {
+        foo as fn(i32) -> i32
+    } else {
+        |x: i32| x
+    };
+
+    // We still can coerce function pointer to non-capturing closure
+    let _ = if true {
+        |x: i32| x
+    } else {
+        foo as fn(i32) -> i32
+    };
+}