build: Install the Bash completion file in the right place
Created by: bochecha
Bash loads completion scripts from 2 directories:
- $(syscondir)/bash_completion.d/
- $(datadir)/bash-completion/completions/
The former is meant to be used by local administrators to drop their own files in, and the latter is what software installers should use.
In the past Hamster used to install its completion file in the former, but this was changed with 1d562615.
Unfortunately that commit had a typo and the last "s" was missing from the path.
This commit fixes that typo.