Merge branch 'jc/exec-cmd-system-path-leak-fix'

The function sometimes returned a non-freeable memory and some
other times returned a piece of memory that must be freed.

* jc/exec-cmd-system-path-leak-fix:
system_path(): always return free'able memory to the caller

diff --cc builtin/help.c
Simple merge

diff --cc builtin/init-db.c
Simple merge

diff --cc exec_cmd.c
Simple merge