[GWP-ASan] Split options_parser and backtrace_sanitizer_common.

Summary:
optional/options_parser and optional/backtrace_sanitizer_common are logically
separate components. They both use sanitizer-common to power their
functionality, but there was an unstated implicit dependency that in order for
backtrace_sanitizer_common to function correctly, one had to also use
options_parser.

This was because options_parser called __sanitizer::InitialiseCommonFlags. This
is a requirement for backtrace_sanitizer_common to work, as the sanitizer
unwinder uses the sanitizer_common flags and will SEGV on a null page if
they're not initialised correctly.

This patch removes this hidden dependency. You can now use
backtrace_sanitizer_common without the requirements of options_parser.

This patch also makes the GWP-ASan unit tests only have a soft dependency on
sanitizer-common. The unit tests previously explicitly used
__sanitizer::Printf, which is now provided under
tests/optional/printf_sanitizer_common. This allows Android to build the unit
tests using their own signal-safe printf().

Reviewers: eugenis

Reviewed By: eugenis

Subscribers: srhines, mgorny, #sanitizers, llvm-commits, vlad.tsyrklevich, morehouse

Tags: #sanitizers, #llvm

Differential Revision: https://reviews.llvm.org/D66684

llvm-svn: 369825
GitOrigin-RevId: 27d69b2f4f6bf9b09755ae2428a4703eb4a4663b
5 files changed