LibCoredump: Show frames from Loader.so if the crash occurs in it

Previously we rejected all entries from Loader.so even if the faulting
address was located in it, i.e. the actual issue was with the dynamic
loader. We no longer do that to make debugging Loader crashes easier.

Userland/Libraries/LibCoredump/Backtrace.h

@@ -47,6 +47,7 @@ private:
     void add_entry(const Reader&, FlatPtr ip);
     ELFObjectInfo const* object_info_for_region(ELF::Core::MemoryRegionInfo const&);
 
+    bool m_skip_loader_so { false };
     ELF::Core::ThreadInfo m_thread_info;
     Vector<Entry> m_entries;
     HashMap<String, NonnullOwnPtr<ELFObjectInfo>> m_debug_info_cache;