scePthreadAttrGetstack, Getstackaddr, Getguardsize, Setguardsize,
Setstack and Setstackaddr threw for a null attribute, a null pointer
argument or a stack below the 16 KiB minimum. FreeBSD's libthr returns
EINVAL for those, as the pthread_attr_* wrappers here and the other
scePthreadAttr calls already do.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>