Don't use full path of libtool
Don't use full path of libtool

This is to be friendly to our OSX users where
the libtool path is very different.

Ref:
* https://github.com/Homebrew/homebrew-core/blob/master/Formula/mariadb.rb#L44..L46

natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2