m4: delete several obsolete macros

m4: delete several obsolete macros

Support for several obsolescent macros has already been deprecated,
and their removal already announced in the documentation and in the
NEWS file.  It's now time to finally remove them.

* m4/dmalloc.m4 (fp_WITH_DMALLOC): Don't define anymore.
* m4/maintainer.m4 (jm_MAINTAINER_MODE): Likewise.
* m4/lispdir.m4 (ud_PATH_LISPDIR): Likewise.
* m4/protos.m4 (fp_C_PROTOTYPES): Likewise.
* m4/ccstdc.m4: Delete file.
* m4/header.m4: Likewise.
* m4/obsol-gt.m4: Likewise.
* m4/obsol-lt.m4: Likewise.
* m4/obsolete.m4: Likewise.
* Makefile.am (dist_automake_ac_DATA): Don't list the deleted '.m4'
files anymore.
* t/confh.sh: Use 'AC_CONFIG_HEADERS' instead of the now-removed
AM_CONFIG_HEADER.
* t/confh.sh: Likewise.
* t/confh4.sh: Likewise.
* t/confh6.sh: Likewise.
* t/confh7.sh: Likewise.
* t/confh8.sh: Likewise.
* t/confsub.sh: Likewise.
* t/stamph2.sh: Likewise.
* t/subdir6.sh: Likewise.
* t/autohdr2.sh: Remove as obsolete.
* t/obsolete.sh: Likewise.
* t/list-of-tests.mk. Don't list the deleted test cases anymore.
* NEWS: Update.
* doc/automake.texi: Likewise.  In particular ...
(Obsolete Macros): Remove this node altogether.

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>