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

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

o) Use ABI, not ISA_* options, to determine whether to compile bits if libkern
required for the ABI the kernel is being built for.
XXX This is implemented in a kind-of nasty way that involves including source
files, but it's still an improvement.
o) Retire ISA_* options since they're unused and were always wrong.

Remove the 'machine mips' from DEFAULTS. Put the proper 'machine mips
mipsel' or 'machine mips mipseb' into the config file (with a few 64's
tossed in for good measure). This will let us build the proper
kernels with different worlds as part of make universe.

Set the svn:eol-style = native and svn:mime-type = text/plain
properties on all files in this tree.

Submitted by: rpaulo@

Place proper svn:keywords tag on all these files. They were created
somehow without them on projects/mips, and that mistake was propigated
over to head.

Submitted by: rpaulo@

Merge from projects/mips to head by hand:

Merge support for very early alchemy port. I wouldn't merge this
except I don't want it to get lost when we retire projects/mips.
Should be consiered pre-alpha at this stage. Also, alchemy is now
owned by rmi, but started out life as a separate processor line, so
I'm leaving it in its own directory rather than try to shoe-horn it
into the unrelated rmi directory. Its future location is an open
question.

- Revert changes accidentally killed by merge operation

First cut at config file for mips alchemy based systems.

First milestone on Alchemy port: Simplest kernel now compiles.