I'm a fan of OpenBSD's more conservative and structured approach to software development, but in this case I must beg to differ. In the linked CVE, OpenBSD was unaffected because "[it] didn't chase the fad of using every Intel cpu feature." The feature in question was user-space hardware debug register access. Without such access, watch-points are borderline unusable[0].
Perhaps prohibiting access to user-space except GDB would be a reasonable compromise. Also, debug registers are not unique to x86: most (all?) CPU architectures have them. So calling it a "fad [...] Intel cpu feature" is a bit unfair.
This is what I had in mind. This obviously impacts some useful gdb features, but such is the nature of OpenBSD.