GitLab

The variable g_is_main_thread is only read from dead code in
irt_manifest.c in the NaCl repo.  It is read from the old SRPC-based
implementation of open_resource(), which isn't accessible because it's
overridden by the Chromium side's implementation of open_resource().

Removing this assignment will allow us to remove irt_manifest.c, which
defines g_is_main_thread.

BUG=https://code.google.com/p/nativeclient/issues/detail?id=3864
TEST=trybots

Review URL: https://codereview.chromium.org/799023003

Cr-Commit-Position: refs/heads/master@{#308172}