sanitizers: increase .clang-format columns to 100

The current (default) line length is 80 columns.
That's based on old hardware and historical conventions.
There are no existent reasons to keep line length that small,
especially provided that our coding style uses quite lengthy
identifiers. The Linux kernel recently switched to 100,
let's start with 100 as well.

This change intentionally does not re-format code.
Re-formatting is intended to happen incrementally,
or on dir-by-dir basis separately.

Reviewed By: vitalybuka, melver, MaskRay

Differential Revision: https://reviews.llvm.org/D106436