Adds a modified options parser (shamefully pulled from Scudo, which
shamefully pulled it from sanitizer-common) to GWP-ASan. This allows
customers (Android) to parse options strings in a common way.
Depends on D94117.
AOSP side of these patches is staged at:
- sepolicy (sysprops should only be settable by the shell, in both root and unrooted conditions): https://android-review.googlesource.com/c/platform/system/sepolicy/+/1517238
- zygote updates: https://android-review.googlesource.com/c/platform/frameworks/base/+/1515009
- bionic changes to add gwp_asan.<process_name> system property, and GWP_ASAN_OPTIONS environment variable: https://android-review.googlesource.com/c/platform/bionic/+/1514989