Fix failure to use shared relro on load from a zip file.

Fix failure to use shared relro on load from a zip file.

When loading from a zip file, record the path to the zip file,
rather that the name of the item within the zip file, as being
the name of the loaded library.

Fixes failure to use shared relro, visible in logcat as:
  E/chromium_android_linker(19916): UseSharedRelro: Could not find libchrome.2192.0.so
  W/chromium_android_linker(19916): Could not use shared RELRO section for libchrome.2192.0.so

Note: load from zip file currently supports only a single shared
library within any given zip file.

BUG=390618

Review URL: https://codereview.chromium.org/667443002

Cr-Commit-Position: refs/heads/master@{#300124}