Implementation notes

Double quine

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0. Concept

It's just a quine, using the same run-length encoding that I have used
in a few other entries before.  But since I haven't been making ASCII
art for a while, I have decided to write two quines at the same time.

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1. Implementation

The technique and encoding used for Serval is pretty much identical to
what was used for Yoshino: http://uguu.org/src_yoshino_c.html

Basically: duplicate code and data using preprocessor macros, and
choose a different layout based on some compile time input.  Actual
implementation for Serval is much more straightforward, selecting
between two layouts based on last digit of compile time.  This layout
selection heuristic was done to make one layout less likely than the
other, to convey the sense that Tsuchinoko is more rare than Serval.

Unlike other quines where I just compile and run to get the formatted
output, this time I formatted the two quines manually to make sure
that they would tokenize properly and recorded the process.  In other
words, everything I have done for Serval is very much not new,
although I am more methodic in doing it now.

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2. Testing

Verified to work on:
- gcc 6.4.0 on cygwin
- gcc 6.1.0 on jslinux
- gcc 4.9.2 on linux
- gcc 4.8.4 on linux
- clang 4.0.1 on cygwin
- clang 3.5.0-10 on linux

Does *not* work with TCC 0.9.25.  This is because TCC's preprocessor
does two things differently from other preprocessors in its
stringizing operation:
- Insert backslash before single quotes.
- Escape \0 as \000.

If it was just the single quotes then I would have worked around that,
but the \000 bits is something that I wasn't prepared for, so
unfortunately Serval doesn't work with TCC.

Other than preprocessor bits, Serval depends on puts() having the
standard signature, since Serval doesn't bother including stdio.h.  On
systems that define puts() as a macro, Serval probably doesn't work.

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3. Finally...

In recent years, I have picked up other hobbies that reward much
faster than writing code, so I have allocated most of my coding time
to work rather than personal projects.

Still, you lose every skill you don't use, and ASCII art is a skill
that I don't want to lose.  It's questionable whether it's a useful
skill or not, but it's appears to be a rare skill that is near
extinction, and extinction of anything is a real shame.