crypto/tls: segfault when calling `tlsrsakex.IncNonDefault()` [1.22 backport]

[gopherbot]

@FiloSottile requested issue #65991 to be considered for backport to the next 1.22 minor release.

@gopherbot please open a Go 1.22 backport issue. This is a severe regression in Go+BoringCrypto mode.

[cagedmantis]

Approved as this is a bug without a workaround.

[mdempsky]

@FiloSottile It looks like this requires both CL 582315 and CL 586755 (no tests) to be backported? I can create the CL, but I'm unfamiliar with Go's BoringSSL-specific details.