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/

stand: update prototypes for md_load and md_load64

These are declared as extern in a number of files (some with the wrong
return type). Centralize this in modinfo.h and remove a few extra stray
declarations as well that are no longer used. No functional change.

Note: I've not tried to cope with the bi_load() functions which are the
same logical thing. These will be handled separately.

Sponsored by: Netflix

stand/efi: allow not exiting boot services

Xen requires that UEFI BootServices are enabled in order to boot, so
introduce a new parameter to bi_load in order to select whether BS
should be exited.

No functional change introduced in this patch, as all current users of
bi_load request BS to be exited. Further changes will make use of this
functionality.

Note the memory map is still appended to the kernel metadata, even
when it could be modified by further calls to the Boot Services, as it
will be used to detect if the kernel has been booted from UEFI.

Sponsored by: Citrix Systems R&D
Reviewed by: tsoome, imp
Differential revision: https://reviews.freebsd.org/D28495

loader: Avoid -Wpointer-to-int cast warnings for Arm and RISC-V

On RISC-V, Clang warns with:

cast to smaller integer type 'unsigned int' from 'void (*)(void *)'

Instead, use %p as the standard format specifier for printing pointers.
Whilst Arm's pointer size is the same as unsigned, it's still cleaner to
use the right thing there too.

Reviewed by: brooks (mentor), emaste
Approved by: brooks (mentor), emaste
Differential Revision: https://reviews.freebsd.org/D25718

EFI: don't call printf after ExitBootServices, since it uses Boot Services

ExitBootServices terminates all boot services including console access.
Attempting to call printf afterwards can result in a crash, depending on the
implementation.

Move any printf statements to before we call bi_load, and remove any that
depend on calling bi_load first.

Reviewed by: imp, tsoome
Differential Revision: https://reviews.freebsd.org/D19374

Prefer uintXX_t to u_intXX_t

A foolish consistency is the hobgoblin of little minds, adored by
little statesmen and philosophers and divines. With consistency a
great soul has simply nothing to do. -- Ralph Waldo Emerson

Move sys/boot to stand. Fix all references to new location

Sponsored by: Netflix