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

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

Replace index() and rindex() calls with strchr() and strrchr().

The index() and rindex() functions were marked LEGACY in the 2001
revision of POSIX and were subsequently removed from the 2008 revision.
The strchr() and strrchr() functions are part of the C standard.

This makes the source code a lot more consistent, as most of these C
files also call into other str*() routines. In fact, about a dozen
already perform strchr() calls.

Use __FBSDID().
Also some minor style cleanups.

Cleanup warnings. Most of these are signed/unsigned warnings, as well as
some added const's.

$Id$ -> $FreeBSD$

Fix a number of memory leaks and other memory-related disorders.

Also, unbreak the breakage introduced at the last revision of module.c.
This changes the semantics of mod_searchfile() (and mod_searchmodule())
to make the caller's responsibility freeing the buffer returned. This
is different from other functions in loader's code, and was done as a
fix for kern/9631. If someone wants to revert this to the original
behavior, don't forget to fix kern/9631 in another way.

This should also fix bin/10462, which was introduced as a result of the
first try at kern/9631 (module.c last revision).

PR: bin/10462
Submitted by: Takanori Saneto <sanewo@ba2.so-net.ne.jp>

Typo in patch application.

PR: kern/9459
Submitted by: "Daniel C. Sobral" <dcs@newsguy.com>

Enable escapes for $ to make it possible to insert variable names into
other variable values.

Initial integration of the i386 bootloader and BTX.

- Discard large amounts of BIOS-related code in favour of the more compact
BTX vm86 interface.
- Build the loader module as ELF, although the resulting object is a.out,
make gensetdefs 32/64-bit sensitive and use a single copy of it.
- Throw away installboot, as it's no longer required.
- Use direct bcopy operations in the i386_copy module, as BTX
maps the first 16M of memory. Check operations against the
detected size of actual memory.

Generic plug-and-play enumerator infrastructure. Query supplied
enumerators, crossreference returned identifiers with a text-format
database and automatically load corresponding modules and dependancies.

Allow quoted strings (single or double) for grouping whitespace separated
items. Eliminate warnings.

New commandline/script parser, supports backslash quoting and environment
variable substitution.

Submitted by: Jordan Hubbard <jkh@freebsd.org>