Enable -requirement-machine-abstract-signatures=on in a couple of tests

There is an edge case where the Requirement Machine produces a different
minimal signature than the GenericSignatureBuilder:

  protocol P {
    associatedtype X where X == Self
  }

  class C : P {
    typealias X = C
  }

  <T where T : P, T : C>

The GenericSignatureBuilder produces <T where T == C> and the Requirement
Machine produces <T where T : C>. The new interpretation makes more sense
with the 'concrete contraction' pre-processing pass that is done now.

The GenericSignatureBuilder's interpretation is slightly more correct,
however the entire conformance is actually invalid if the class is not
final, and we warn about it now.

I'm going to see if we can get away with this minor ABI change without
breaking anything.

Author: slavapestov

test/SILGen/class_conforms_with_default_concrete_self.swift

@@ -1,4 +1,5 @@
-// RUN: %target-swift-emit-silgen %s | %FileCheck %s
+// RUN: %target-swift-emit-silgen %s -requirement-machine-abstract-signatures=on | %FileCheck %s
+// RUN: %target-swift-emit-silgen %s -requirement-machine-abstract-signatures=on -disable-requirement-machine-concrete-contraction | %FileCheck %s
 
 public protocol P {
   associatedtype A : Q where A.B == Self
@@ -24,5 +25,6 @@ public class D : Q {
   public typealias B = C
 }
 
-// CHECK-LABEL: sil shared [transparent] [serialized] [thunk] [ossa] @$s41class_conforms_with_default_concrete_self1CCAA1PA2aDP25hasDefaultImplementation1yyFTW : $@convention(witness_method: P) (@in_guaranteed C) -> () {
-// CHECK-LABEL: sil shared [transparent] [serialized] [thunk] [ossa] @$s41class_conforms_with_default_concrete_self1CCAA1PA2aDP25hasDefaultImplementation2yyqd__1BQyd__RszAA1QRd__lFTW : $@convention(witness_method: P) <τ_0_0 where τ_0_0 == C><τ_1_0 where τ_1_0 : Q, τ_1_0.B == C> (@in_guaranteed τ_1_0, @in_guaranteed C) -> () {
+// CHECK-LABEL: sil shared [transparent] [serialized] [thunk] [ossa] @$s41class_conforms_with_default_concrete_self1CCAA1PA2aDP25hasDefaultImplementation1yyFTW : $@convention(witness_method: P) <τ_0_0 where τ_0_0 : C> (@in_guaranteed τ_0_0) -> () {
+
+// CHECK-LABEL: sil shared [transparent] [serialized] [thunk] [ossa] @$s41class_conforms_with_default_concrete_self1CCAA1PA2aDP25hasDefaultImplementation2yyqd__1BQyd__RszAA1QRd__lFTW : $@convention(witness_method: P) <τ_0_0 where τ_0_0 : C><τ_1_0 where τ_0_0 == τ_1_0.B, τ_1_0 : Q> (@in_guaranteed τ_1_0, @in_guaranteed τ_0_0) -> () {

validation-test/compiler_crashers_2_fixed/0189-sr10033.swift

@@ -1,4 +1,5 @@
-// RUN: %target-swift-frontend -emit-ir -verify %s
+// RUN: %target-swift-frontend -emit-ir -verify -requirement-machine-abstract-signatures=on %s
+// RUN: %target-swift-frontend -emit-ir -verify -requirement-machine-abstract-signatures=on -disable-requirement-machine-concrete-contraction %s
 
 protocol P1 {
   associatedtype A2 : P2 where A2.A1 == Self