The documentation of the cross translation unit analysis mentioned a
certain flag of `CodeChecker` (an external open source tool that can be
used to drive the static analysis), but the information about it was
obsolete: apparently the name of the flag, the names of the possible
values, and the default value were all changed.
Currently `CodeChecker analyze --help` displays this flag as
```
--ctu-ast-mode {load-from-pch,parse-on-demand}
Choose the way ASTs are loaded during CTU analysis. Only available if
CTU mode is enabled. Mode 'load-from-pch' generates PCH format
serialized ASTs during the 'collect' phase. Mode 'parse-on-demand'
only generates the invocations needed to parse the ASTs. Mode 'load-
from-pch' can use significant disk-space for the serialized ASTs,
while mode 'parse-on-demand' can incur some runtime CPU overhead in
the second phase of the analysis. (default: parse-on-demand)
```
and I tried to follow this in the commands that I adjusted.
Note that this documentation file probably contains other obsolete
details as well, but I didn't try to find or fix them.
6540c93aa9