BlockGuardOsTest: Add exception for getrlimit.

This method doesn't need blockguard support.

Bug: 63004717
Test: vogar --mode=host BlockGuardOsTest

(cherry picked from commit e05b7bef31baa5fd28d675b3eeef0909591481b4)

Change-Id: Ia4225b8c35b90ee798940991242260318f359b63
1 file changed