[GRASS-dev] ZSTD compressor not compiled by default if available

[Nikos Alexandris]

Dears,

do I understand it wrong that, if available in a system, the ZSTD
compressor _should_ be compiled by default?  Or does the choice for
"default" concern only the `r.compress` module?

In trunk:
```
./configure --help |grep zstd
  --with-zstd             support Zstandard functionality (default: no)
  --with-zstd-includes=DIRS
  --with-zstd-libs=DIRS   ZSTD library files are in DIRS
```

Thank you, Nikos