[GSB] Use Type instead of ProtocolDecl in a couple of diagnostics [NFC]

Not all redundant type constraints have an associated protocol decl, e.g 'T : Any'.

Author: hamishknight

include/swift/AST/DiagnosticsSema.def

@@ -1913,11 +1913,11 @@ ERROR(requires_generic_param_same_type_does_not_conform,none,
 ERROR(requires_same_concrete_type,none,
       "generic signature requires types %0 and %1 to be the same", (Type, Type))
 WARNING(redundant_conformance_constraint,none,
-        "redundant conformance constraint %0: %1", (Type, ProtocolDecl *))
+        "redundant conformance constraint %0: %1", (Type, Type))
 NOTE(redundant_conformance_here,none,
      "conformance constraint %1: %2 %select{written here|implied here|"
      "inferred from type here}0",
-     (unsigned, Type, ProtocolDecl *))
+     (unsigned, Type, Type))
 
 ERROR(unsupported_recursive_requirements, none,
       "requirement involves recursion that is not currently supported", ())

lib/AST/GenericSignatureBuilder.cpp

@@ -6292,7 +6292,7 @@ void GenericSignatureBuilder::checkConformanceConstraints(
     // Remove any self-derived constraints.
     removeSelfDerived(*this, entry.second, entry.first);
 
-    checkConstraintList<ProtocolDecl *, ProtocolDecl *>(
+    checkConstraintList<ProtocolDecl *, Type>(
       genericParams, entry.second,
       [](const Constraint<ProtocolDecl *> &constraint) {
         return true;
@@ -6324,7 +6324,7 @@ void GenericSignatureBuilder::checkConformanceConstraints(
       None,
       diag::redundant_conformance_constraint,
       diag::redundant_conformance_here,
-      [](ProtocolDecl *proto) { return proto; },
+      [](ProtocolDecl *proto) { return proto->getDeclaredType(); },
       /*removeSelfDerived=*/false);
   }
 }