31cf95cec7
We should clear the single step flag when entering a signal hander and set it when returning. This fixes the ptrace__PT_STEP_with_signal test. While here add support for userspace to set the single step bit as on x86. This can be used by userspace for self tracing. Reviewed by: kib Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D34170