Fix RTLD_NEXT/DEFAULT lookup

RTLD_NEXT/DEFAULT lookup should not skip handle lookup
in the case when the load group is RTLD_GLOBAL.

Note that there is a difference between load group is local group.
The local group includes externally referenced libraries where
the load group does not. The external reference in this context is a
DT_NEEDED library that belongs to a previously loaded group.

Bug: http://b/72237367
Test: bionic-unit-tests --gtest_filter=dl*
Change-Id: I8997cc961c13a5396f1756161798b45ed1cab16c