Do not dlclose after failed reinit.

Update stale comment.

The reinitialization logic is tested in HeapprofdEndToEnd::ReInit in https://android.googlesource.com/platform/external/perfetto/+/master/src/profiling/memory/heapprofd_end_to_end_test.cc

Change-Id: Id496ee02e208d4f4cea7129b47ef327fb2bb67f2