Deprecate DLOPEN_GNOME_KEYRING flag

GnomeKeyringLoader will be moved into a separate utility.
This change makes GnomeKeyringLoader simpler to build on and easier
to move.

Currently, GnomeKeyringLoader compiles different code, depending on
whether keyring is statically linked. Now it will only do dynamic
loading. The only place that requires static linking is tests, and they
don't need GnomeKeyringLoader to do it for them.

BUG=602624

Review-Url: https://codereview.chromium.org/2191873002
Cr-Commit-Position: refs/heads/master@{#408924}
6 files changed