Update tests following merge.

Author: bricknerb

toolchain/check/testdata/interop/cpp/function/reference.carbon

@@ -879,8 +879,8 @@ fn F() {
 // CHECK:STDOUT:   %S: type = class_type @S [concrete]
 // CHECK:STDOUT:   %ptr: type = ptr_type %S [concrete]
 // CHECK:STDOUT:   %pattern_type: type = pattern_type %ptr [concrete]
-// CHECK:STDOUT:   %.041: type = cpp_overload_set_type @ReturnsLValue [concrete]
-// CHECK:STDOUT:   %.03d: %.041 = cpp_overload_set_value @ReturnsLValue [concrete]
+// CHECK:STDOUT:   %.041: type = cpp_overload_set_type @<null name> [concrete]
+// CHECK:STDOUT:   %.03d: %.041 = cpp_overload_set_value @<null name> [concrete]
 // CHECK:STDOUT:   %ReturnsLValue.type: type = fn_type @ReturnsLValue [concrete]
 // CHECK:STDOUT:   %ReturnsLValue: %ReturnsLValue.type = struct_value () [concrete]
 // CHECK:STDOUT: }
@@ -892,7 +892,7 @@ fn F() {
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %S.decl: type = class_decl @S [concrete = constants.%S] {} {}
-// CHECK:STDOUT:   %.03d: %.041 = cpp_overload_set_value @ReturnsLValue [concrete = constants.%.03d]
+// CHECK:STDOUT:   %.03d: %.041 = cpp_overload_set_value @<null name> [concrete = constants.%.03d]
 // CHECK:STDOUT:   %ReturnsLValue.decl: %ReturnsLValue.type = fn_decl @ReturnsLValue [concrete = constants.%ReturnsLValue] {
 // CHECK:STDOUT:     <elided>
 // CHECK:STDOUT:   } {
@@ -923,8 +923,8 @@ fn F() {
 // CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
 // CHECK:STDOUT:   %S: type = class_type @S [concrete]
 // CHECK:STDOUT:   %pattern_type.7da: type = pattern_type %S [concrete]
-// CHECK:STDOUT:   %.c60: type = cpp_overload_set_type @ReturnsRValue [concrete]
-// CHECK:STDOUT:   %.99d: %.c60 = cpp_overload_set_value @ReturnsRValue [concrete]
+// CHECK:STDOUT:   %.c60: type = cpp_overload_set_type @<null name> [concrete]
+// CHECK:STDOUT:   %.99d: %.c60 = cpp_overload_set_value @<null name> [concrete]
 // CHECK:STDOUT:   %ReturnsRValue.type: type = fn_type @ReturnsRValue [concrete]
 // CHECK:STDOUT:   %ReturnsRValue: %ReturnsRValue.type = struct_value () [concrete]
 // CHECK:STDOUT:   %type_where: type = facet_type <type where .Self impls <CanDestroy>> [concrete]
@@ -941,7 +941,7 @@ fn F() {
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %S.decl: type = class_decl @S [concrete = constants.%S] {} {}
-// CHECK:STDOUT:   %.99d: %.c60 = cpp_overload_set_value @ReturnsRValue [concrete = constants.%.99d]
+// CHECK:STDOUT:   %.99d: %.c60 = cpp_overload_set_value @<null name> [concrete = constants.%.99d]
 // CHECK:STDOUT:   %ReturnsRValue.decl: %ReturnsRValue.type = fn_decl @ReturnsRValue [concrete = constants.%ReturnsRValue] {
 // CHECK:STDOUT:     <elided>
 // CHECK:STDOUT:   } {
@@ -982,8 +982,8 @@ fn F() {
 // CHECK:STDOUT:   %S: type = class_type @S [concrete]
 // CHECK:STDOUT:   %const: type = const_type %S [concrete]
 // CHECK:STDOUT:   %pattern_type.9be: type = pattern_type %const [concrete]
-// CHECK:STDOUT:   %.c99: type = cpp_overload_set_type @ReturnConstLValue [concrete]
-// CHECK:STDOUT:   %.bf8: %.c99 = cpp_overload_set_value @ReturnConstLValue [concrete]
+// CHECK:STDOUT:   %.c99: type = cpp_overload_set_type @<null name> [concrete]
+// CHECK:STDOUT:   %.bf8: %.c99 = cpp_overload_set_value @<null name> [concrete]
 // CHECK:STDOUT:   %ReturnConstLValue.type: type = fn_type @ReturnConstLValue [concrete]
 // CHECK:STDOUT:   %ReturnConstLValue: %ReturnConstLValue.type = struct_value () [concrete]
 // CHECK:STDOUT:   %type_where: type = facet_type <type where .Self impls <CanDestroy>> [concrete]
@@ -1000,7 +1000,7 @@ fn F() {
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %S.decl: type = class_decl @S [concrete = constants.%S] {} {}
-// CHECK:STDOUT:   %.bf8: %.c99 = cpp_overload_set_value @ReturnConstLValue [concrete = constants.%.bf8]
+// CHECK:STDOUT:   %.bf8: %.c99 = cpp_overload_set_value @<null name> [concrete = constants.%.bf8]
 // CHECK:STDOUT:   %ReturnConstLValue.decl: %ReturnConstLValue.type = fn_decl @ReturnConstLValue [concrete = constants.%ReturnConstLValue] {
 // CHECK:STDOUT:     <elided>
 // CHECK:STDOUT:   } {