Fix OsTest for different possible setgroups() return values.

setgroups() can return EINVAL if the number of
groups passed is > NGROUPS_MAX.

This means that the call in this test could fail
with EINVAL is NGROUPS_MAX is == 0.

Address this possibility by checking and choosing
an appropriate error code to test against.

Bug: 69023954
Test: vogar OsTest
Change-Id: Id03cdb73a9cc3df31f22b25dc28079aac609a35f