Disable tests that aren't expected to work now

Author: DougGregor

test/diagnostics/pretty-printed-diagnostics.swift

@@ -1,7 +1,7 @@
 // RUN: not %target-swift-frontend -diagnostic-style=swift -typecheck %/s 2>&1 | %FileCheck %s
 
 // Note: test has not been updated to match the swift-syntax style.
-// XFAIL: OS=macosx
+// REQUIRES: newswiftsyntaxstyle
 
 1 + 2
 

test/diagnostics/pretty-printed-source-loc-directive-diags.swift

@@ -1,7 +1,7 @@
 // RUN: not %target-swift-frontend -diagnostic-style=swift -typecheck %/s 2>&1 | %FileCheck %s
 
 // Note: test has not been updated to match the swift-syntax style.
-// XFAIL: OS=macosx
+// REQUIRES: newswiftsyntaxstyle
 
 // Error split between the real file and a virtual one.
 #sourceLocation(file: "abc.swift", line: 9)