More consistently retry system calls on EINTR

We were not retrying an accept() call om EINTR, resulting in occasional
zygote failures. This fixes that, and a few other calls documented
to potentially return EINTR. This is based on a quick seacrh of the
two files affected by this CL.

Bug: 193753947
Bug: 187992348
Test: Build and boot AOSP
Change-Id: Icbfb38be5110607c121545e5c200ce65d1eefbfe