14c620719c
This PR brings back limited debuginfo which allows for nice backtraces and breakpoints, but omits any info about variables and types. The `-g` and `--debuginfo` command line options have been extended to take an optional argument: `-g0` means no debug info. `-g1` means line-tables only. `-g2` means full debug info. Specifying `-g` without argument is equivalent to `-g2`. Fixes #12280