Automake: How to fix Libtool library used but 'LIBTOOL' is undefined

Problem

You are trying to configure a project using automake but you see error messages such as

src/Makefile.am:3: error: Libtool library used but 'LIBTOOL' is undefined
src/Makefile.am:3:   The usual way to define 'LIBTOOL' is to add 'LT_INIT'
src/Makefile.am:3:   to 'configure.ac' and run 'aclocal' and 'autoconf' again.
src/Makefile.am:3:   If 'LT_INIT' is in 'configure.ac', make sure
src/Makefile.am:3:   its definition is in aclocal's search path.

Solution

Install libtool using e.g.

sudo apt install libtool