Replace AC_SUBST_FILE in configure with include in Makefiles.
* configure.ac (DEPDIR, MKDEPDIR, deps_frag, lwlib_deps_frag)
(oldxmenu_deps_frag, lisp_frag): Remove output variables/files.
(AUTO_DEPEND): New output variable.
* lwlib/Makefile.in (AUTO_DEPEND): New, set by configure.
(DEPFLAGS, MKDEPDIR): Set directly via conditional.
(lwlib_deps_frag): Replace by conditional include.
* lwlib/autodeps.mk: Remove file.
* oldXMenu/Makefile.in (AUTO_DEPEND): New, set by configure.
(DEPFLAGS, MKDEPDIR): Set directly via conditional.
(oldxmenu_deps_frag): Replace by conditional include.
* oldXMenu/autodeps.mk: Remove file.
* src/Makefile.in (AUTO_DEPEND): New, set by configure.
(DEPFLAGS, MKDEPDIR): Set directly via conditional.
(lisp_frag): Replace by an include.
(deps_frag): Replace by conditional include.
* src/autodeps.mk: Remove file.