Revert "Merge pull request #18420 from eeckstein/disable-test-4.2"

The underlying issue has been fixed.

This reverts commit 3f7d681, reversing
changes made to 0b76949.

Author: jrose-apple

test/ClangImporter/CoreGraphics_test.swift

@@ -1,7 +1,5 @@
 // RUN: %target-swift-frontend -module-name=cgtest -emit-ir -O %s | %FileCheck %s
 
-// REQUIRES: rdar42775178
-
 // Test some imported CG APIs
 import CoreGraphics