[llvm][DebugInfo][ObjC] Make sure we link backing ivars to their DW_TAG_APPLE_property

Depends on:
* llvm#165373
* llvm#165401

When an Objective-C property has a backing ivar, we would previously not add a `DW_AT_APPLE_property` to the ivar's `DW_TAG_member`. This is what was intended based on the [Objective-C DebugInfo docs](https://github.com/llvm/llvm-project/blob/main/llvm/docs/SourceLevelDebugging.rst#proposal) but is not what LLVM currently generates.

LLDB currently doesn't ever try linking the `ObjCPropertyDecl`s to their `ObjCIvarDecl`s, but if we wanted to, this debug-info patch is a pre-requisite.

Author: Michael137

llvm/test/DebugInfo/Generic/objc-property.ll

@@ -3,49 +3,55 @@
 ; CHECK: DW_TAG_structure_type
 ; CHECK:   DW_AT_name ("Foo")
 ;
-; CHECK:   DW_TAG_APPLE_property
+; CHECK:   0x[[AUTO_SYNTH:[0-9a-f]+]]: DW_TAG_APPLE_property
 ; CHECK:     DW_AT_APPLE_property_name ("autoSynthProp")
 ; CHECK:     DW_AT_APPLE_property_attribute
 ; CHECK-SAME: DW_APPLE_PROPERTY_assign, DW_APPLE_PROPERTY_readwrite,
 ; CHECK-SAME: DW_APPLE_PROPERTY_atomic, DW_APPLE_PROPERTY_unsafe_unretained
 ;
-; CHECK:   DW_TAG_APPLE_property
+; CHECK:   0x[[SYNTH:[0-9a-f]+]]: DW_TAG_APPLE_property
 ; CHECK:     DW_AT_APPLE_property_name ("synthProp")
 ; CHECK:     DW_AT_APPLE_property_attribute
 ; CHECK-SAME: DW_APPLE_PROPERTY_assign, DW_APPLE_PROPERTY_readwrite,
 ; CHECK-SAME: DW_APPLE_PROPERTY_atomic, DW_APPLE_PROPERTY_unsafe_unretained
 ;
-; CHECK:   DW_TAG_APPLE_property
+; CHECK:   0x[[GET:[0-9a-f]+]]: DW_TAG_APPLE_property
 ; CHECK:     DW_AT_APPLE_property_name ("customGetterProp")
 ; CHECK:     DW_AT_APPLE_property_getter   ("customGetter")
 ; CHECK:     DW_AT_APPLE_property_attribute
 ; CHECK-SAME: DW_APPLE_PROPERTY_getter, DW_APPLE_PROPERTY_assign, DW_APPLE_PROPERTY_readwrite,
 ; CHECK-SAME: DW_APPLE_PROPERTY_atomic, DW_APPLE_PROPERTY_unsafe_unretained
 ;
-; CHECK:   DW_TAG_APPLE_property
+; CHECK:   0x[[SET:[0-9a-f]+]]: DW_TAG_APPLE_property
 ; CHECK:     DW_AT_APPLE_property_name ("customSetterProp")
 ; CHECK:     DW_AT_APPLE_property_setter   ("customSetter:")
 ; CHECK:     DW_AT_APPLE_property_attribute
 ; CHECK-SAME: DW_APPLE_PROPERTY_assign, DW_APPLE_PROPERTY_readwrite,
 ; CHECK-SAME: DW_APPLE_PROPERTY_setter, DW_APPLE_PROPERTY_atomic, DW_APPLE_PROPERTY_unsafe_unretained
 ;
-; CHECK:   DW_TAG_APPLE_property
+; CHECK:   0x[[ACCESSORS:[0-9a-f]+]]: DW_TAG_APPLE_property
 ; CHECK:     DW_AT_APPLE_property_name ("customAccessorsProp")
 ; CHECK:     DW_AT_APPLE_property_getter   ("customGetter")
 ; CHECK:     DW_AT_APPLE_property_setter   ("customSetter:")
 ; CHECK:     DW_AT_APPLE_property_attribute
 ; CHECK-SAME: DW_APPLE_PROPERTY_getter, DW_APPLE_PROPERTY_assign, DW_APPLE_PROPERTY_readwrite,
 ; CHECK-SAME: DW_APPLE_PROPERTY_setter, DW_APPLE_PROPERTY_atomic, DW_APPLE_PROPERTY_unsafe_unretained
 ;
-; FIXME: missing link between DW_TAG_member and the associated DW_TAG_APPLE_property
 ; CHECK:   DW_TAG_member
-; CHECK-NOT: DW_AT_APPLE_property
+; CHECK:     DW_AT_name ("someBackingIvar")
+; CHECK:     DW_AT_APPLE_property (0x[[SYNTH]])
+;
 ; CHECK:   DW_TAG_member
-; CHECK-NOT: DW_AT_APPLE_property
+; CHECK:     DW_AT_name ("_autoSynthProp")
+; CHECK:     DW_AT_APPLE_property (0x[[AUTO_SYNTH]])
+;
 ; CHECK:   DW_TAG_member
-; CHECK-NOT: DW_AT_APPLE_property
+; CHECK:     DW_AT_name ("_customGetterProp")
+; CHECK:     DW_AT_APPLE_property (0x[[GET]])
+;
 ; CHECK:   DW_TAG_member
-; CHECK-NOT: DW_AT_APPLE_property
+; CHECK:     DW_AT_name ("_customSetterProp")
+; CHECK:     DW_AT_APPLE_property (0x[[SET]])
 
 !llvm.module.flags = !{!7, !8}
 !llvm.dbg.cu = !{!13}