ignore missing /proc/<pid>/setgroups files

When running on older kernels that lack setgroups, the write failure
causes minijail to abort.  Short of having every caller detect the
kernel support and selectively calling disable_setgroups, ignore the
write failure directly when it's ENOENT.

Bug: None
Test: running on newer kernels works, as does older kernels

Change-Id: I424cb749fec0f76cc4278a8a7581b168fbe50485
1 file changed