Sourcegenerator only run when not referenced

[CptWesley]

Closes #4

Changes

• Source generators no longer run if Backport.System.Threading.Lock is referenced during compilation.

Notes

• I didn't bump the versions yet, since I'm not sure what your preferred way of working is in that regard.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100%. Comparing base (55a7b16) to head (c34503a).
Report is 4 commits behind head on master.

Additional details and impacted files

@@          Coverage Diff          @@
##           master     #5   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           3      3           
  Lines          19     19           
=====================================
  Hits           19     19           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[MarkCiliaVincenti]

LGTM code wise, I will make some experiments and see if it works, thanks

[MarkCiliaVincenti]

Bravo! Really awesome trick!