* m4/depend.m4 (AM_DEP_TRACK): Use AC_SUBST([AMDEPBACKSLASH])

* m4/depend.m4 (AM_DEP_TRACK): Use AC_SUBST([AMDEPBACKSLASH])
normally, what is wrong is that automake outputs a variable
definition for it, hence...
* automake.in (scan_one_autoconf_file): don't.
* m4/depout.m4 (_AM_OUTPUT_DEPENDENCY_COMMANDS): New, extracted
from...
(AM_OUTPUT_DEPENDENCY_COMMANDS): here.  Adjust.
Use AC_CONFIG_COMMANDS.
(_AM_OUTPUT_DEPENDENCY_COMMANDS): Use AS_DIRNAME and AS_MKDIR_P.