configure.ac: use "command -v" instead of "type -p"

[bjornfor]

"type -p" is a Bash thing, whereas "command -v" is specified by POSIX
(more portable).

[domenkozar]

Can you point to docs claiming that? :)

[bjornfor]

http://pubs.opengroup.org/onlinepubs/9699919799/utilities/command.html
http://pubs.opengroup.org/onlinepubs/9699919799/utilities/type.html

The first link shows that "command -v" is in POSIX and the latter that "type" (in POSIX) doesn't support any flags. "command -v" works in e.g. dash and bash, whereas "type -p" only works in bash.

[bjornfor]

Some practical examples:

$ bash -c "type -p getconf"
/run/current-system/sw/bin/getconf
$ bash -c "command -v getconf"
/run/current-system/sw/bin/getconf
$ dash -c "type -p getconf"
-p: not found
getconf is /run/current-system/sw/bin/getconf
### the above command exited with status 127
$ dash -c "command -v getconf"
/run/current-system/sw/bin/getconf