RequirementMachine: Relax cross-check assert for areSameTypeParameterInContext()

The GSB and RequirementMachine sometimes disagree on whether two
type parameters that have both been equated to the same concrete
type belong to the same equivalence class or not.

Since in practice, this distinction does not matter, relax the
assert here.

Author: slavapestov

lib/AST/GenericSignature.cpp

@@ -896,15 +896,19 @@ bool GenericSignatureImpl::areSameTypeParameterInContext(Type type1,
     auto gsbResult = computeViaGSB();
 
     if (gsbResult != rqmResult) {
-      llvm::errs() << "RequirementMachine::areSameTypeParameterInContext() is broken\n";
-      llvm::errs() << "Generic signature: " << GenericSignature(this) << "\n";
-      llvm::errs() << "First dependent type: "; type1.dump(llvm::errs());
-      llvm::errs() << "Second dependent type: "; type2.dump(llvm::errs());
-      llvm::errs() << "\n";
-      llvm::errs() << "GenericSignatureBuilder says: " << gsbResult << "\n";
-      llvm::errs() << "RequirementMachine says: " << rqmResult << "\n";
-      getRequirementMachine()->dump(llvm::errs());
-      abort();
+      auto firstConcreteType = getConcreteType(type1);
+      auto secondConcreteType = getConcreteType(type2);
+      if (!firstConcreteType->isEqual(secondConcreteType)) {
+        llvm::errs() << "RequirementMachine::areSameTypeParameterInContext() is broken\n";
+        llvm::errs() << "Generic signature: " << GenericSignature(this) << "\n";
+        llvm::errs() << "First dependent type: "; type1.dump(llvm::errs());
+        llvm::errs() << "Second dependent type: "; type2.dump(llvm::errs());
+        llvm::errs() << "\n";
+        llvm::errs() << "GenericSignatureBuilder says: " << gsbResult << "\n";
+        llvm::errs() << "RequirementMachine says: " << rqmResult << "\n";
+        getRequirementMachine()->dump(llvm::errs());
+        abort();
+      }
     }
 
     return rqmResult;