Hi all,

>> This patch enables -fsanitize-recover for KASan by default. This causes
>> KASan to continue execution after error in case of inline
>> instrumentation. This feature is needed because
>> - reports during early bootstrap won't even be printed
>> - needed to run all tests w/o rebooting machine for every test
>> - needed for interactive work on desktop

This is the third version of patch which renames -fsanitize-recover to 
-fubsan-recover and introduces -fasan-recover (enabled by default for 
KASan). It also moves flag handling to finish_options per Jakub's request.

Bootstrapped and regtested on x64.

-Y