MFC 256293:
Sanitize the %eflags returned by BIOS routines.  Some BIOS routines enter
protected mode and may leave protected-mode-specific flags like PSL_NT set
when they return to real mode.  This can cause a fault when BTX re-enters
protected mode after the BIOS mode returns.

PR:		amd64/182740
MFC 256274:
Ignore attempts to set the nmbcluster sysctls to their current value
rather than failing with an error.