* automake.in (handle_configure): Distribute all AC_CONFIG_HEADERS

* automake.in (handle_configure): Distribute all AC_CONFIG_HEADERS
sources, and without using require_file.  Define %CONFIG_H_DEPS%
and %FIRST_CONFIG_HIN% while processing remake-hdr.am.
* lib/am/remake-hdr.am (%STAMP%): Use %CONFIG_H_DEPS% instead
of (srcdir)/%CONFIG_HIN%.  Output the $(srcdir)/%CONFIG_HIN%
rule only for the first header (i.e., if %FIRST_CONFIG_HIN%).
* tests/autohdr4.test: New file.
* tests/Makefile.am (TESTS): Add autohdr4.test.
* tests/config.test: Do not grep, run things to see if they work.