Update lilac config_machines.xml from version 2 to version 3.

[ekluzek]

In ctsm5.1.dev172 we updated externals for config_machines.xml from version 2 to version 3. Right now both are allowed, but I expect eventually only version 3 will be supported. So we likely will need to switch at some point. And it will be easier to support if it's more similar to the way machines are currently setup in ccs_config/machines.

@billsacks and I worked out what we think needs to happen. The machine_configuration directory that's created needs a top level config_machines.xml file that will look something like this:

<config_machines version="3.0">
  <NODENAME_REGEX>
    <value MACH="ctsm-build">.*</value>
  </NODENAME_REGEX>

  <default_run_suffix>
    <default_run_exe>$CIME_OUTPUT_ROOT/case/bld/cesm.exe </default_run_exe>
    <default_run_misc_suffix> >> cesm.log 2>&amp;1 </default_run_misc_suffix>
  </default_run_suffix>

</config_machines>

beneath that will be a directory called "ctsm-build" for the LILAC generic machine with the normal contents of the config_machines.xml from before...

So something like...

  <machine MACH="ctsm-build">

    <!-- Text description of the machine -->
    <DESC>Temporary build information for a CTSM build</DESC>

    <!-- OS: the operating system of this machine. Passed to cppflags for
         compiled programs as -DVALUE  recognized are LINUX, AIX, Darwin, CNL -->
    <OS>$OS</OS>
.
.
.
  </machine>

I think the cmake macros file should also be in a cmake_macros subdirectory and named ctsm-build.cmake.

[billsacks]

I'm not sure, but it might also work to skip nodename_regex (as we're currently doing, I think), and just put all of the config_machines stuff at the top level. That's what I have for my current machine port in my .cime directory. Also note that, even though the ccs_config stuff puts MACH.cmake files under cmake_macros, that isn't the case for a user-defined machine port like this, so I don't think that needs to move (and it might not work to move it). This is all a bit of speculation, though, since I haven't tested this with the lilac build myself.