GNU libtool is a generic library support script. Libtool hides the complexity of using shared libraries behind a consistent, portable interface.
More information: https://www.gnu.org/software/libtool/
The system image of libtool can be found at /bin/libtool
and corresponds to version 2.4.6.
See the documentation of libtool available at https://www.gnu.org/software/libtool/manual/libtool.html.