mem-ruby,scons: Add scons option for multiple protocols

This change does many things, but they must all be atomically done.

**USER FACING CHANGE**: The Ruby protocols in Kconfig have changed names
(they are now the same case as the SLICC file names). So, after this
commit, your build configurations need to be updated. You can do so by
running `scons menuconfig <build dir>` and selecting the right ruby
options. Alternatively, if you're using a `build_opts` file, you can run
`scons defconfig build/<ISA> build_opts/<ISA>` which should update your
config correctly.

Detailed changes are described below.

Kconfig changes:

- Kconfig files in ruby now must all be declared in the ruby/Kconfig
  file
- All of the protocol names are changed to match their slicc file names
  including the case
- A new option is available called "Use multiple protocols" which should
  be selected if multiple protocols are selected. This is only used to
  set the PROTOCOL variable to "MULTIPLE" when in multiple mode.
- The PROTOCOL variable can now be "MULTIPLE" which means it will be
  ignored. If it's not "MULTIPLE" then it holds the "main" protocol,
  which is necessary for backwards compatibility with the Ruby.py files.

Ruby config changes:

To make this change backwards compatible with Ruby.py, this change adds
a new "protocol" config called MULTIPLE.py which is used to allow the
user to set a "--protocol" option on the command line. This is only
needed if you are using a gem5 binary with multiple protocols but need
to use Ruby.py.

stdlib changes:

- Make the coherence protocol file behave like the ISA file
- Add a function to get the coherence protocol from the `CacheHierarchy`
  like we do with the ISA in the `Processor`.
  - Use this function where `get_runtime_coherence_protocol` was used
- Update the requires code to work with the ne CoherenceProtocol
- Fix a typo in the AMD Hammer name and also add the missing MSI
  protocol

Scons changes:

- In Ruby we now gather up all of the protocols and build them all if
  there are multiple protocols
- There's some bending over backwards to tell the user if they are using
  an out of date gem5.build/config file and how to update it
- Note that multiple ruby protocols adds a significant amount of time to
  the build since we have to run slicc twice for each file.

build_opts:

- Update all files with new names
- Add a new NULL_All_Ruby that will be used for testing

Signed-off-by: Jason Lowe-Power <jason@lowepower.com>

tests/gem5/x86_boot_tests/configs/x86_boot_exit_run.py

@@ -42,7 +42,6 @@ from gem5.components.processors.cpu_types import (
 from gem5.components.processors.simple_processor import SimpleProcessor
 from gem5.isas import ISA
 from gem5.resources.resource import obtain_resource
-from gem5.runtime import get_runtime_coherence_protocol
 from gem5.simulate.simulator import Simulator
 from gem5.utils.requires import requires
 
@@ -196,7 +195,9 @@ motherboard.set_workload(workload)
 # Begin running of the simulation. This will exit once the Linux system boot
 # is complete.
 print("Running with ISA: " + processor.get_isa().name)
-print("Running with protocol: " + get_runtime_coherence_protocol().name)
+print(
+    "Running with protocol: " + cache_hierarchy.get_coherence_protocol().name
+)
 print()
 
 print("Beginning simulation!")