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: Use c99 structure initialization for nfs_fsops

Sponsored by: Netflix

loader: net_open() should not replace f->f_devdata

net_open() does replace f_devdata with pointer to netdev_sock,
this will cause memory leak when device is closed, but also does
alter the devopen() logic.

We should store &netdev_sock to dev->d_opendata instead, this
would preserve and follow the devopen() logic.

Fixes network boot on aarch64 (tested by bz).

Reviewed-by: imp
MFC After: 2 weeks
Differential Revision: https://reviews.freebsd.org/D32227

Logging improvements to loader::nfs

Include the server IP address when logging nfs_open(), add a few missing
"\n"s, and correct a typo.

Reviewed by: kevans
MFC after: 2 weeks
Sponsored by: Panasas
Differential Revision: https://reviews.freebsd.org/D22346

libsa: assignment to char * from u_char *

Cast to char * instead of u_char *

Initialize variables we later free so they aren't used
uninitialized in the error path.
Remove unused variables.

Sponsored by: Netflix

libsa: Const-ify buffer argument of write(2) analog

Reported by: kevans
Reviewed by: delphij, eadler, imp, kevans
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D14482

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

Sponsored by: Netflix