Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Let all .c and .S files under lib/csu consistently use the __FBSDID()
macro for identification, instead of several different hand-rolled
variants (plain .ident, .ascii, etc).

Put in an attempt at stack trace/unwind records.

Mostly cosmetic. Use indentation that is reasonably close to other
ia64 *.S files in our tree (eg: locore.s). Put the rest of the args
in the .section lines.

Reviewed by: dfr

Add missing crti.S and crtn.S files. I have tested these with -static
linking only. They may require some gp relative tweaks for dynamic use.