Handle auto-depend with configure.

Handle auto-depend with configure.

* make-dist (src): Include *.mk.
* config.bat: Concatenate deps.mk onto the end of src/Makefile.
* configure.in (DEPFLAGS, MKDEPDIR): New output variables.
(deps_frag): New output file.
(AUTO_DEPEND): Remove this definition.

* src/Makefile.in (DEPDIR): New constant.
(DEPFLAGS): Set with configure, not cpp.
(MKDEPDIR): New, set by configure.
(.c.o, .m.o, ecrt0.o): Use $MKDEPDIR.
(clean): Use $DEPDIR.
(deps_frag): Include from configure.
Move static/dynamic dependency stuff to deps.mk/autodeps.mk.
* src/deps.mk, src/autodeps.mk: New files, extracted from Makefile.in.

* msdos/sed1v2.inp (DEPFLAGS, deps_frag): Edit to empty.
(MKDEPDIR): Edit to ':'.