* automake.in (%ignored_configure_vars): New variable.

* automake.in (%ignored_configure_vars): New variable.
(scan_autoconf_traces): Trace for _AM_SUBST_NOTMAKE and fill
%ignored_configure_vars.
(define_configure_variable): Declare ignored configure variables
as VAR_SILENT.  Do not special-case AMDEPBACKSLASH and ANSI2KNR
w.r.t. VAR_SILENT.
* m4/substign.m4: New file.
* m4/Makefile.am (dist_m4data_DATA): Add substign.m4.
* m4/cond.m4: _AM_SUBST_IGNORE $1_TRUE and $1_FALSE (PR automake/477).
* m4/depend.m4: _AM_SUBST_IGNORE AMDEPBACKSLASH.
* m4/protos.m4: _AM_SUBST_IGNORE ANSI2KNR.
* tests/cond.test: Make sure TEST_FALSE and TEST_TRUE are not defined.
* tests/amsubst.test: New file.
* tests/Makefile.am (TESTS): Add it.