minijail: do not use gcc designator extension.
minijail: do not use gcc designator extension.

BUG=chromium:240348
TEST=CFLAGS="clang" FEATURES="test" emerge-lumpy chromeos-minijail passes.

Change-Id: Ie56992d6e487f9badf14b62a47010fe0e7882847
Reviewed-on: https://gerrit.chromium.org/gerrit/51004
Reviewed-by: Will Drewry <72416dde44ea762d19e3a7a555e3b59ce98f8eea@chromium.org>
Tested-by: Yunlian Jiang <8ca9e07d8da722742b3f5a8340e0afab8cf1248e@chromium.org>
Commit-Queue: Yunlian Jiang <8ca9e07d8da722742b3f5a8340e0afab8cf1248e@chromium.org>

omegaup/minijail,omegaup/minijail,omegaup/minijail,omegaup/minijail