Automake-1.13 removed long obsolete AM_CONFIG_HEADER completely (
http://lists.gnu.org/archive/html/automake/2012-12/msg00038.html ) and errors
out upon seeing it.
Attached patch replaces it with proper AC_CONFIG_HEADERS.
I'm mass submitting automake-1.13 fixes. Please see what you can do so
I don't need to do the same when automake-1.14 comes out:
Note that fixing this one problem alone does not make libevent to work with automake-1.13 - there's also use of $(top_srcdir) in TESTS issue.