[ubsan] Recover by default, use -fno-sanitize-recover to disable

Patches attached.



0001-ubsan-Recover-by-default-use-fno-sanitize-recover-to.patch (16.3 KB)

0001-ubsan-Update-test-now-that-check-recovery-is-default.patch (2.12 KB)

Patches should go to cfe-commits@; dropping cfe-dev@ via BCC.

+def fsanitize_recover : Flag<["-"], "fsanitize-recover">,
+ Group<f_clang_Group>,
+ HelpText<"Attempt to recover from failed
sanitizer checks when possible">;

I don't know if we have an official policy on this, but we generally
don't have help text for the default values of flags (it just adds
noise to the -help output).

Otherwise, LGTM. Thanks!