Libcore: Add classloader to dex cache

Live dex caches must keep their associated classloader live. Otherwise
the classloader may get unloaded, attempting to free DexFiles which
cannot be unregistered.

Companion to ART change.

Test: art/test/testrunner/testrunner.py -b --host
Bug: 149098478

(cherry-picked from commit 271b4054b825efca3176c4ac11565e33cff5d09a)
Merged-In: I0eed5b3b46ed681c739d6923a57d0878afbba1a7

Change-Id: I0eed5b3b46ed681c739d6923a57d0878afbba1a7
1 file changed