mem: Move ruby protocols into a directory called ruby_protocol.

Now that the gem5 protocols are split out, it would be nice to put them
in their own protocol directory. It's also confusing to have files
called *_protocol which are not in the protocol directory.

Change-Id: I7475ee111630050a2421816dfd290921baab9f71
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/20230
Reviewed-by: Gabe Black <gabeblack@google.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>

ruby: Revamp standalone SLICC script

There was some bitrot in the standalone SLICC script (util/slicc and
src/mem/slicc/main.py). Fix the changes to the SLICC interface and also
add some better documentation.

Change-Id: I91c0ec78d5072fba83edf32b661ae67967af7822
Signed-off-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-on: https://gem5-review.googlesource.com/10561
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>

scons: Switch from the print statement to the print function.

Starting with version 3, scons imposes using the print function instead
of the print statement in code it processes. To get things building
again, this change moves all python code within gem5 to use the
function version. Another change by another author separately made this
same change to the site_tools and site_init.py files.

Change-Id: I2de7dc3b1be756baad6f60574c47c8b7e80ea3b0
Reviewed-on: https://gem5-review.googlesource.com/8761
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Gabe Black <gabeblack@google.com>

slicc: add a protocol statement and an include statement
All protocols must specify their name
The include statement allows any file to include another file.

slicc: cleanup slicc code and make it less verbose

slicc: tweak file enumeration for scons
Right now .cc and .hh files are handled separately, but then
they're just munged together at the end by scons, so it
doesn't buy us anything. Might as well munge from the start
since we'll eventually be adding generated Python files
to the list too.

slicc: Pure python implementation of slicc.
This is simply a translation of the C++ slicc into python with very minimal
reorganization of the code. The output can be verified as nearly identical
by doing a "diff -wBur".

Slicc can easily be run manually by using util/slicc