The kernel code was using some <asm> headers that included a mix
of hardware-specific information (typically found in Tilera <arch>
headers) and structures, enums, and function declarations supporting
the disassembly function of the tile-desc.c sources.

This change refactors that code so that a hardware-specific, but
OS- and application-agnostic header, is created: <arch/opcode.h>.
This header is then exported to userspace along with the other
<arch> headers and can be used to build userspace code; in particular,
it is used by glibc as part of implementing the backtrace() function.

The new header, together with a header that specifically describes
the disassembly code (<asm/tile-desc.h> with _32 and _64 variants),
replaces the old <asm/opcode-tile*.h> and <asm/opcode_constants*.h>
headers.

As part of this change, we are also renaming the 32-bit constants
from TILE_xxx to TILEPRO_xxx to better reflect the fact that they
are specific to the TILEPro architecture, and not to TILE-Gx
and any successor "tile" architecture chips.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

This support was partially present in the existing code (look for
"__tilegx__" ifdefs) but with this change you can build a working
kernel using the TILE-Gx toolchain and ARCH=tilegx.

Most of these files are new, generally adding a foo_64.c file
where previously there was just a foo_32.c file.

The ARCH=tilegx directive redirects to arch/tile, not arch/tilegx,
using the existing SRCARCH mechanism in the top-level Makefile.

Changes to existing files:

- <asm/bitops.h> and <asm/bitops_32.h> changed to factor the
  include of <asm-generic/bitops/non-atomic.h> in the common header.

- <asm/compat.h> and arch/tile/kernel/compat.c changed to remove
  the "const" markers I had put on compat_sys_execve() when trying
  to match some recent similar changes to the non-compat execve.
  It turns out the compat version wasn't "upgraded" to use const.

- <asm/opcode-tile_64.h> and <asm/opcode_constants_64.h> were
  previously included accidentally, with the 32-bit contents.  Now
  they have the proper 64-bit contents.

Finally, I had to hack the existing hacky drivers/input/input-compat.h
to add yet another "#ifdef" for INPUT_COMPAT_TEST (same as x86_64).

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> [drivers/input]