stand: Automated cleanup of cdefs and other formatting

Apply the following automated changes to try to eliminate
no-longer-needed sys/cdefs.h includes as well as now-empty
blank lines in a row.

Remove /^#if.*\n#endif.*\n#include\s+<sys/cdefs.h>.*\n/
Remove /\n+#include\s+<sys/cdefs.h>.*\n+#if.*\n#endif.*\n+/
Remove /\n+#if.*\n#endif.*\n+/
Remove /^#if.*\n#endif.*\n/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/types.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/param.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/capsicum.h>/

Sponsored by: Netflix

Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

Fix the EFI_DEBUG case, prio_str is only used when EFI_DEBUG is unset.

Sponsored by: Innovate UK

loader.efi: replace HandleProtocol() with OpenProtocol()

The HandleProtocol() is deprecated interface and we should use OpenProtocol()
instead. Moreover, in some firmware implementation(s), the HandleProtocol()
does return device path using static storage, so we can not keep the value
returned there. With same firmware, the OpenProtocol() does return data we
do not need to clone.

Reviewed by: imp
Differential Revision: https://reviews.freebsd.org/D21162

Break out the disk selection protocol from the rest of boot1.

Segregate the disk probing and selection protocol from the rest of the
boot loader.

Reviewed by: tsoome, bcran
Differential Revision: https://reviews.freebsd.org/D20547