libtoolize: Consider adding "AC_CONFIG_MACRO_DIR([m4])" to configure.ac and
libtoolize: rerunning libtoolize, to keep the correct libtool macros in-tree.
libtoolize: Consider adding "-I m4" to ACLOCAL_AMFLAGS in Makefile.am.
Signed-off-by: Jan Engelhardt <jengelh@medozas.de>