Make libdl.so be loaded after libc.so

Make sure that libdl is always after libc on the command line.
Simplifies the logic to always support system_shared_libs for
sdk and vndk builds.

For backwards compatibility without updating lots of Android.bp
files, allow libdl to be listed in shared_libs as long as it
is also in system_shared_libs or libc is not in system_shared_libs.

Remove all the places that libdl is added as a dependency, since
it will always be present unless explicitly removed now.

Bug: 62815515
Test: m -j checkbuild
Merged-In: I0233178ffea87a2f0b82190746022476304a68e2
Change-Id: I0233178ffea87a2f0b82190746022476304a68e2
(cherry picked from commit ef88ae23)