Try to make pg_dump_splitsort.py compilable with nuitka

[akaihola]

In #13, @oldcai writes:

I tested it with a 444G .sql file and it finished within 523m22.189s.

Let's see if we can compile pg_dump_splitsort.py with nuitka, and document the performance gain if it works.

[akaihola]

Benchmark on my Lenovo Carbon X1 Gen 9 with NixOS:

• 18MB SQL, Python 3.11.4: 0.5 s
• 18MB SQL, Nuitka 1.4.8: 0.5 s
• 100MB SQL, Python 3.11.4: 11.6 s
• 100MB SQL, Nuitka 1.4.8: 10.2 s

[akaihola]

$ nuitka3 pgtricks/pg_dump_splitsort.py
Nuitka-Options:INFO: Used command line options: pgtricks/pg_dump_splitsort.py
Nuitka-Options:WARNING: You did not specify to follow or include anything but main program. Check options and make sure that is intended.
Nuitka:WARNING: Using very slow fallback for ordered sets, please install 'ordered-set' PyPI package for best Python compile time performance.
Nuitka:INFO: Starting Python compilation with Nuitka '1.4.8' on Python '3.10' commercial grade 'not installed'.
Nuitka:INFO: Completed Python level compilation and optimization.
Nuitka:INFO: Generating source code for C backend compiler.
Nuitka:INFO: Running data composer tool for optimal constant value handling.
Nuitka:INFO: Running C compilation via Scons.
Nuitka-Scons:INFO: Backend C compiler: gcc (gcc).
Nuitka-Scons:INFO: Backend linking program with 7 files (no progress information available).
Nuitka-Scons:WARNING: You are not using ccache.
Nuitka:INFO: Keeping build directory 'pg_dump_splitsort.build'.
Nuitka:INFO: Successfully created 'pg_dump_splitsort.bin'.