On macOS Apple provides a script called libtool that is unrelated to GNU libtool (and there is no libtoolize). In order to not conflict with Apple's libtool, when GNU libtool is installed on macOS it is customary to install it with a "g" prefix: glibtool and glibtoolize. Update autogen.sh to find glibtoolize if there is no libtoolize.
On macOS Apple provides a script called libtool that is unrelated to GNU libtool (and there is no libtoolize). In order to not conflict with Apple's libtool, when GNU libtool is installed on macOS it is customary to install it with a "g" prefix: glibtool and glibtoolize. Update autogen.sh to find glibtoolize if there is no libtoolize.