improvements in Unicode tables generation code

I have accumulated a few patches to improve the output of the scripts in
src/backend/utils/mb/Unicode/ to be less non-standard-looking and fix a
few other minor things in that area.

v1-0001-Make-Unicode-makefile-more-parallel-safe.patch

The makefile rule that calls UCS_to_most.pl was written incorrectly for
parallel make. The script writes all output files in one go, but the
rule as written would call the command once for each output file in
parallel.

v1-0002-Make-UCS_to_most.pl-process-encodings-in-sorted-o.patch

This mainly just helps eyeball the output while debugging the previous
patch.

v1-0003-Remove-some-whitespace-in-generated-C-output.patch

Improve a small formatting issue in the output.

v1-0004-Simplify-code-generation-code.patch

This simplifies the code a bit, which helps with the next patch.

v1-0005-Fix-indentation-in-generated-output.patch

This changes the indentation in the output from two spaces to a tab.

I haven't included the actual output changes in the last patch, because
they would be huge, but the idea should be clear.

All together, these make the output look closer to how pgindent would
make it.