cmd: env: Add `indirect` to indirectly set values

This allows an ergonomic-enough approximation of ${!variable} expansion.
This could be used the following way:

```
for target in ${boot_targets}; do
   env indirect target_name target_name_${target}
   # ...
done
```

Assuming `target_name_mmc0` and similar are set appropriately.

A default value can be optionally provided.

Note: this acts on environment variables, not hush variables.

Signed-off-by: Samuel Dionne-Riel <[email protected]>
Cc: Simon Glass <[email protected]>
Cc: "Marek Behún" <[email protected]>
[trini: Don't enable by default]

0 files changed, 0 insertions, 0 deletions