Fix tests/untrusted_check for nacl_arm_glibc
Fix tests/untrusted_check for nacl_arm_glibc

The new glibc implementation of abort dies with the usual signal,
unlike the old nacl_x86_glibc.

BUG= https://code.google.com/p/nativeclient/issues/detail?id=3068
TEST= trybots + scons platform=arm --nacl_glibc run_untrusted_check_test_irt
R=phosek@chromium.org, mseaborn@chromium.org

Review URL: https://codereview.chromium.org/1123563002

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