Move CPU features into its own static library.

Move CPU features into its own static library.

CPU features has outgrown its original x86-only roots and is used in
more than just the validators. Move it out of there as a second step to
cleaning up this code.

The eventual goal is for CPU features to have similar interfaces for all
CPUs, as well as for some features to work when host and target are
different (e.g. validate an ARM nexe with a certain ARM feature set on
an x86 box).

This CL doesn't change any code beyond:
- moving it;
- updating the includes/include guards;
- fixing silly build scripts.

R= bsy@chromium.org

Committed: https://src.chromium.org/viewvc/native_client?view=rev&revision=10590

[JF, 2013-01-11 20:49:33]

I seem to have gyp working now, PTAL.

[bsy, 2013-01-11 21:11:30]

one nit.  o/w lgtm.

https://codereview.chromium.org/11864002/diff/10006/src/trusted/cpu_features/...
File src/trusted/cpu_features/arch/x86/cpu_xgetbv.S (right):

https://codereview.chromium.org/11864002/diff/10006/src/trusted/cpu_features/...
src/trusted/cpu_features/arch/x86/cpu_xgetbv.S:33: #endif
isn't this a tad dangerous -- if this is not NACL_x86, we get a text label with
no code.  if any arm/mips code actually called this function, we'd get control
passed to whatever code happens to follow.  maybe use NACL_HALT in an else
clause, to be defensive?

[Roland McGrath, 2013-01-11 21:15:00]

https://codereview.chromium.org/11864002/diff/10006/src/trusted/cpu_features/...
File src/trusted/cpu_features/arch/x86/cpu_xgetbv.S (right):

https://codereview.chromium.org/11864002/diff/10006/src/trusted/cpu_features/...
src/trusted/cpu_features/arch/x86/cpu_xgetbv.S:33: #endif
In other cases we just put #error in an #else clause.
But this is an x86-only file and should not be compiled for other machines
anyway.  So I really wonder what the introduction of the #if was meant for.  It
seems suspect.

[bsy, 2013-01-11 21:19:53]

https://codereview.chromium.org/11864002/diff/10006/src/trusted/cpu_features/...
File src/trusted/cpu_features/arch/x86/cpu_xgetbv.S (right):

https://codereview.chromium.org/11864002/diff/10006/src/trusted/cpu_features/...
src/trusted/cpu_features/arch/x86/cpu_xgetbv.S:33: #endif
the problem is that this is getting built for all platforms.  the idea is that
the goal is that ncval would run on any platform and validate code targeting any
other platform.

[JF, 2013-01-12 00:15:19]

As discussed I changed things a bit so that ARM and MIPS target are built
regardless of host, but x86 target is only build when host is x86.

This means that Vlad's generic validator can still work on x86 (as it does
today), but will require separating host and target code in the x86 C file
before it can work on other platforms (which is already the case before my CL).

PTAL, I've also kicked of new try jobs.

[bsy, 2013-01-12 00:23:14]

lgtm if the bots dance.