sanitizer_common: split LibIgnore into fast/slow paths
LibIgnore is checked in every interceptor.
Currently it has all logic in the single function
in the header, which makes it uninlinable.
Split it into fast path (no libraries ignored)
and slow path (have ignored libraries).
It makes the fast path inlinable (single load).
Reviewed By: vitalybuka
Differential Revision: https://reviews.llvm.org/D105719