Update aclocal.m4, Makefile.am and configure.ac

[bkmgit]

When running sh ./bootstrap the following messages are produced:

libtoolize: putting auxiliary files in '.'.
libtoolize: copying file './ltmain.sh'
libtoolize: You should add the contents of the following files to 'aclocal.m4':
libtoolize:   '/usr/share/aclocal/libtool.m4'
libtoolize:   '/usr/share/aclocal/ltoptions.m4'
libtoolize:   '/usr/share/aclocal/ltsugar.m4'
libtoolize:   '/usr/share/aclocal/ltversion.m4'
libtoolize:   '/usr/share/aclocal/lt~obsolete.m4'
libtoolize: Consider adding 'AC_CONFIG_MACRO_DIRS([m4])' to configure.ac,
libtoolize: and rerunning libtoolize and aclocal.
libtoolize: Consider adding '-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
configure.ac:14: installing './compile'
configure.ac:7: installing './missing'
Makefile.am:1: warning: 'INCLUDES' is the old name for 'AM_CPPFLAGS' (or '*_CPPFLAGS')
Makefile.am:6: warning: source file '${top_srcdir}/mylib/tcode.c' is in a subdirectory,
Makefile.am:6: but option 'subdir-objects' is disabled
automake: warning: possible forward-incompatibility.
automake: At least a source file is in a subdirectory, but the 'subdir-objects'
automake: automake option hasn't been enabled.  For now, the corresponding output
automake: object file(s) will be placed in the top-level directory.  However,
automake: this behaviour will change in future Automake versions: they will
automake: unconditionally cause object files to be placed in the same subdirectory
automake: of the corresponding sources.
automake: You are advised to start using 'subdir-objects' option throughout your
automake: project, to avoid future incompatibilities.
Makefile.am: installing './depcomp'
include/Makefile.am:1: warning: '%'-style pattern rules are a GNU make extension
include/Makefile.am:4: warning: '%'-style pattern rules are a GNU make extension
include/Makefile.am:7: warning: '%'-style pattern rules are a GNU make extension

The files should be updated to remove these warnings. These messages are produced with

• automake 1.16.1
• autoconf 2.69
• libtoolize 2.4.6