Revert "XFAIL test under Linux"

This reverts commit 7e23237.

Author: adrian-prantl

lldb/test/API/lang/swift/cxx_interop/forward/test-cxx-class/TestCxxClass.py

@@ -9,7 +9,6 @@
 class TestClass(TestBase):
 
     @swiftTest
-    @expectedFailureAll(oslist=['linux'], bugnumber='rdar://104681506')
     def test_class(self):
         self.build()
         self.runCmd('setting set target.experimental.swift-enable-cxx-interop true')