Update info on some deny-list entries.

(Some info has been relocated to blockers in Buganizer)

Also remove libjemalloc5 and fmtlib_ndk from the deny list as they don't seem to need to be there at the moment.

Test: bazel build //bionic/...
Test: build/bazel/scripts/run_presubmits.sh

Change-Id: I87e9dd3d4a83291efbcc15d6b99187b57d45ad18