mem: Put gem5 protocols in their own directory.

This reduces clutter in the src/mem directory, and makes it clear that
those protocols are for the classic gem5 memory system, not ruby, TLM,
etc.

Change-Id: I6cf6b21134d82f4f01991e4fe92dbea8c7e82081
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/20231
Tested-by: kokoro <noreply+kokoro@google.com>
Maintainer: Gabe Black <gabeblack@google.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>

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>

scons: Move Transform and termcap functionality into their own files.

Change-Id: Ica08e93f3873a7eafd02fe7d44c3bdbf0ce7f6b7
Reviewed-on: https://gem5-review.googlesource.com/5565
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

Ruby: Modify Scons so that we can put .sm files in extras
Also allows for header files which are required in slicc generated
code to be in a directory other than src/mem/ruby/slicc_interface.

build scripts: Made minor modifications to reduce build overhead time.

1. --implicit-cache behavior is default.
2. makeEnv in src/SConscript is conditionally called.
3. decider set to MD5-timestamp
4. NO_HTML build option changed to SLICC_HTML (defaults to False)

BuildEnv: Eliminate RUBY as build environment variable
This patch replaces RUBY with PROTOCOL in all the SConscript files as
the environment variable that decides whether or not certain components
of the simulator are compiled.

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: have a central mechanism for creating a code_formatter.
This makes it easier to add global variables like protocol

ruby: Added a Scons option to prevent HTML file creation

scons: ignore blank lines in .slicc files

ruby: Make SLICC-generated objects SimObjects.
Also add SLICC support for state-machine parameter defaults
(passed through to Python as SimObject Param defaults).

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: whack some of Nate's leftover debug code

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

scons: add slicc and ply to sys.path and PYTHONPATH so everyone has access

slicc: generate html by default

slicc: update parser.py for changes in slicc language.

scons: update SCons files for changes in ruby.

ruby: add RUBY sticky option that must be set to add ruby to the build
Default is false

ruby: Migrate all of ruby and slicc to SCons.
Add the PROTOCOL sticky option sets the coherence protocol that slicc
will parse and therefore ruby will use. This whole process was made
difficult by the fact that the set of files that are output by slicc
are not easily known ahead of time. The easiest thing wound up being
to write a parser for slicc that would tell me. Incidentally this
means we now have a slicc grammar written in python.