[Sanitizers] Remove OOM/BadRequest allocator error handling policies.

Summary:
Remove the generic error nadling policies and handle each allocator error
explicitly. Although more verbose, it allows for more comprehensive, precise
and actionable allocator related failure reports.

This finishes up the series of changes of the particular sanitizer
allocators, improves the internal allocator error reporting and removes
now unused policies.

Reviewers: vitalybuka, cryptoad

Subscribers: kubamracek, delcypher, #sanitizers, llvm-commits

Differential Revision: https://reviews.llvm.org/D48328

llvm-svn: 335147