Switch from AM_PROG_MKDIR_P to AC_PROG_MKDIR_P to avoid automake warning.
Signed-off-by: Allan McRae <firstname.lastname@example.org>
It is advised to switch to using '$(MKDIR_P)' instead of '$(mkdir_p)' in Makefile.*
too. Our only use of this in the the "Makefile.in.in" files from gettext. As these
produce no warnings or errors yet, I think it best to wait on gettext to update these