Multiple buildRuns still run simultaneously

[suntong]

          I know the root cause now, it's because when you save your code in a short period of time, air will start duplicate processes, but doesn't have any lock for it.

Originally posted by @xiantang in https://github.com/cosmtrek/air/issues/457#issuecomment-1754768521

[suntong]

Thanks for fixing #216, now the "port address already in use" issue has been fixed.

Yet, the air will still start duplicate build processes, like I originally reported in https://github.com/cosmtrek/air/issues/216#issuecomment-1751531229

• It dramatically slow down the build process on my tiny VPS, and
• it results in duplicated error messages. The worst case I got was over 10 duplicated error message copies, taking a huge chuck of my scrollback spaces.

Please doublecheck.

[suntong]

Eventually the processes grow so out of the control,

that even ^C to stop it will take several minutes :( :(

[xiantang]

https://github.com/cosmtrek/air/commit/4603314db840710d1762e1e4a1527cfc9c7d90c0 should be fix by