Make sys_resource test more robust.

Bug: 19482626

"ulimit -c xxx" command may run before bionic-unit-tests.
Make sure sys_resource test fails gently in that case.

Change-Id: Ic3b5ed8b20acba56df8c5ef082c88e5050e761aa
(cherry picked from commit 4853f40f3fb6664cb1b7af97b6b3e795717026b1)
1 file changed