MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation

Archs using in-tree gcc were broken with `warning: redundant
redeclaration of 'cap_no_rights' [-Wredundant-decls]`.

Sponsored by:	The FreeBSD Foundation

This way we can properly show descriptors with URLs in them.

Reviewed by:	hselasky@
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation

Reported by:	ilya at bakulin.de

Reported by:	Mark Millard
Pointy-hat to:	jhibbits

Summary:
Some hypervisor exceptions on POWER architecture only save state to HSRR0/HSRR1.
Until we have bhyve on POWER, use a lightweight exception frontend which copies
HSRR0/HSRR1 into SRR0/SRR1, and run the normal trap handler.

The first user of this is the Hypervisor Virtualization Interrupt, which targets
the XIVE interrupt controller on POWER9.

Reviewed By: nwhitehorn
Differential Revision: https://reviews.freebsd.org/D15487

a KASSERT

without initializing