Apply Doug's patch to loosen test to just check for error

Author: airspeedswift

test/Generics/validate_stdlib_generic_signatures.swift

@@ -1,6 +1,10 @@
 // Verifies that all of the generic signatures in the standard library are
 // minimal and canonical.
 
-// RUN: %target-typecheck-verify-swift -typecheck -verify-generic-signatures Swift
+// RUN: not %target-typecheck-verify-swift -typecheck -verify-generic-signatures Swift 2> %t.log
+
+// RUN: grep -c "error:" %t.log | count 1
+// RUN: %FileCheck %s < %t.log
+
+// CHECK: error: unexpected error produced: generic requirement 'τ_0_0.Index : Strideable' is redundant in <τ_0_0 where τ_0_0 : RandomAccessCollection, τ_0_0.Index : Strideable, τ_0_0.Indices == Range<τ_0_0.Index>, τ_0_0.Index.Stride == Int>
 
-// expected-no-diagnostics