fixup github actions examples

[mdavidsaver]

Overall, things just worked. I had to make a couple of changes to the example config files though.

• git w/ recursive checkout
• Assume cue.py in .ci/ sub-module
• No SET=test01

I also removed the extra configurations from the RTEMS targets since these are (I think) not used. RTEMS builds are always static+debug.

I'm seeing failures with the windows debug builds which I don't understand. There are a lot of "missing debugging", which I assume is due to our not handling pdb files. I'm perplexed that one is an error though. (especially the "OK (0)" part)

  dbRecStd.lib(ts.obj) : warning LNK4204: 'D:\a\pvxs\pvxs\test\O.windows-x64-static\vc140.pdb' is missing debugging information for referencing module; linking object as if no debug info
  dbCore.lib(dbUnitTest.obj) : fatal error LNK1318: Unexpected PDB error; OK (0) 'D:\a\pvxs\pvxs\test\O.windows-x64-static\vc140.pdb'

The remaining failures are likely my doing.

[mdavidsaver]

I had to quote 7.0 as an environment variable value to keep it from being treated as a numeric constant. And attempting a git clone with --branch 7.

env:
  BASE: "7.0"

My main "complaint" with github actions in general is how dense and repetitive the configuration file is. If I'm going to replace travis-ci (seems like a reasonable goal), then I'll want to test different Base and gcc versions. At present, it looks like this means repeating the whole job block, including steps:, for each combination.

The situation would be improved when/if yaml anchors are supported.

[ralphlange]

Thanks a lot!
Cut'n'paste everywhere...
I should add jobs that try to use the example files. But the module structure is different. Not sure if this would work.