[lldb/ObjC] Make the NonPointerIsaCache initialization lazy

The objc_debug_isa_class_mask magic value that the objc runtime vends
is now initialized using a static initializer instead of a constant
value. The runtime plugin itself will be initialized before the value
is computed and as a result, the cache will get the wrong value.

Making the creation of the NonPointerIsaCache fully lazy fixes this.

GitOrigin-RevId: c4fee95746caad924cd33ace36bad44a3dbffd79
2 files changed