Use PASE perl to run manual generation scripts.
As PASE perl is not aware of all possible input file encoding, convert
all files to UTF-8 upon build start (this might be lengthy).
OS/400 terminal emulation may only offer 76 columns, thus a new -c
parameter has been added to the managen program, defining the allowed
width.
If perl is not available, omit generation and disable online manual.
Closes#14289
Build scripts must be executed by the os/400 shell (sh), not bash which
is a PASE program.
Shell function get_make_vars() escaping reworked to match $() subcommand
construct.
Follow-up to 8a622baf9eCloses#13366
- use `$()` instead of backticks, and re-arrange double-quotes inside.
- add missing `|| exit 1` to `cd` calls. (could be dropped by using `set -eu`.)
- add `-n` to a few `if`s.
- shorten redirections by using `{} >` (as shellcheck recommended).
- silence warnings where variables were detected as unused (SC2034).
- a couple misc updates to silence warnings.
- switch to bash shebang for `-ot` feature.
- split two lines to unbreak syntax highlighting in my editor. (`$(expr \`, `$(dirname \`)
Also enable CI checks for OS/400 shell scripts.
Ref: #13307Closes#13309
