sys: 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

sys: Remove ancient SCCS tags.

Remove ancient SCCS tags from the tree, automated scripting, with two
minor fixup to keep things compiling. All the common forms in the tree
were removed with a perl script.

Sponsored by: Netflix

sys: Remove $FreeBSD$: one-line .c pattern

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

libkern: remove bcopy

Unused since ba96f37758412151 ("Use __builtin for various mem* and b* (e.g. bzero)
routines.")

File name remains to reduce churn.

Sponsored by: Rubicon Communications, LLC ("Netgate")

libkern: clean up empty lines in .c and .h files

Simplify things a little

Rather than include a copy for memmove to call bcopy to call memcpy
(which handles overlapping copies), make memmove a strong reference to
memcpy to save the two calls.

Differential Revision: https://reviews.freebsd.org/D15374

Move MI-ish bcopy routine to libkern

riscv and powerpc have nearly identical bcopy.c that's
supposed to be mostly MI. Move it to the MI libkern.

Differential Revision: https://reviews.freebsd.org/D15374