Use a DrylandEcology fork of pcg

[dschlaep]

• branch "feature_sw2" of the DrylandEcology fork of pcg contains a commit that "Fix[es] function declaration without a prototype"

• close #353 "clang strict-prototypes warnings"

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 72.80%. Comparing base (055bb84) to head (5094acc).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## release/devel_v8.0.0 #394 +/- ## ===================================================== Coverage 72.80% 72.80% ===================================================== Files 20 20 Lines 5640 5640 ===================================================== Hits 4106 4106 Misses 1534 1534 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.