the Clang version used in the Linux ARM CI to Clang 19.
nullability-completeness is an all-or-nothing warning, and it is
enabled by default. If anything is annotated, everything has to be
annotated.
There are a few types of fixes in this change. The most common is just
to add missing annotations. In a few cases, some SFINAE methods are
changed not to use pointers at all. In some cases, like
cord_internal.h, I removed the single annotation as that is easier
than doing the entire complicated file for now. cordz_test_helpers.h
uses GoogleTest macros, which bring in pointers that can't easily be
annotated, so I removed the annotations from this file as well.
Tests are also opted-out of the warning.
I'm not sure why the x86 Clang version didn't pick these issues up.
PiperOrigin-RevId: 755844859
Change-Id: I7d7f4cc4f6d779f52c86a4d96e07880341244491
