diff --git a/aclocal/ax_lib_event.m4 b/aclocal/ax_lib_event.m4
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+dnl @synopsis AX_LIB_EVENT([MINIMUM-VERSION])
+dnl
+dnl Test for the libevent library of a particular version (or newer).
+dnl
+dnl If no path to the installed libevent is given, the macro will first try
+dnl using no -I or -L flags, then searches under /usr, /usr/local, /opt,
+dnl and /opt/libevent.
+dnl If these all fail, it will try the $LIBEVENT_ROOT environment variable.
+dnl
+dnl This macro requires that #include <sys/types.h> works and defines u_char.
+dnl
+dnl This macro calls:
+dnl   AC_SUBST(LIBEVENT_CPPFLAGS)
+dnl   AC_SUBST(LIBEVENT_LDFLAGS)
+dnl   AC_SUBST(LIBEVENT_LIBS)
+dnl
+dnl And (if libevent is found):
+dnl   AC_DEFINE(HAVE_LIBEVENT)
+dnl
+dnl It also leaves the shell variables "success" and "ax_have_libevent"
+dnl set to "yes" or "no".
+dnl
+dnl NOTE: This macro does not currently work for cross-compiling,
+dnl       but it can be easily modified to allow it.  (grep "cross").
+dnl
+dnl @category InstalledPackages
+dnl @category C
+dnl @version 2007-09-12
+dnl @license AllPermissive
+dnl
+dnl Copyright (C) 2009 David Reiss
+dnl Copying and distribution of this file, with or without modification,
+dnl are permitted in any medium without royalty provided the copyright
+dnl notice and this notice are preserved.
+
+dnl Input: ax_libevent_path, WANT_LIBEVENT_VERSION
+dnl Output: success=yes/no
+AC_DEFUN([AX_LIB_EVENT_DO_CHECK],
+         [
+          # Save our flags.
+          CPPFLAGS_SAVED="$CPPFLAGS"
+          LDFLAGS_SAVED="$LDFLAGS"
+          LIBS_SAVED="$LIBS"
+          LD_LIBRARY_PATH_SAVED="$LD_LIBRARY_PATH"
+
+          # Set our flags if we are checking a specific directory.
+          if test -n "$ax_libevent_path" ; then
+            LIBEVENT_CPPFLAGS="-I$ax_libevent_path/include"
+            LIBEVENT_LDFLAGS="-L$ax_libevent_path/lib"
+            LD_LIBRARY_PATH="$ax_libevent_path/lib:$LD_LIBRARY_PATH"
+          else
+            LIBEVENT_CPPFLAGS=""
+            LIBEVENT_LDFLAGS=""
+          fi
+
+          # Required flag for libevent.
+          LIBEVENT_LIBS="-levent"
+
+          # Prepare the environment for compilation.
+          CPPFLAGS="$CPPFLAGS $LIBEVENT_CPPFLAGS"
+          LDFLAGS="$LDFLAGS $LIBEVENT_LDFLAGS"
+          LIBS="$LIBS $LIBEVENT_LIBS"
+          export CPPFLAGS
+          export LDFLAGS
+          export LIBS
+          export LD_LIBRARY_PATH
+
+          success=no
+
+          # Compile, link, and run the program.  This checks:
+          # - event.h is available for including.
+          # - event_get_version() is available for linking.
+          # - The event version string is lexicographically greater
+          #   than the required version.
+          AC_LANG_PUSH([C])
+          dnl This can be changed to AC_LINK_IFELSE if you are cross-compiling,
+          dnl but then the version cannot be checked.
+          AC_RUN_IFELSE([AC_LANG_PROGRAM([[
+          #include <sys/types.h>
+          #include <event.h>
+          ]], [[
+          const char* lib_version = event_get_version();
+          const char* wnt_version = "$WANT_LIBEVENT_VERSION";
+          for (;;) {
+            /* If we reached the end of the want version.  We have it. */
+            if (*wnt_version == '\0') {
+              return 0;
+            }
+            /* If the want version continues but the lib version does not, */
+            /* we are missing a letter.  We don't have it. */
+            if (*lib_version == '\0') {
+              return 1;
+            }
+            /* If we have greater than what we want.  We have it. */
+            if (*lib_version > *wnt_version) {
+              return 0;
+            }
+            /* If we have less, we don't. */
+            if (*lib_version < *wnt_version) {
+              return 1;
+            }
+            lib_version++;
+            wnt_version++;
+          }
+          return 0;
+          ]])], [
+          success=yes
+          ])
+          AC_LANG_POP([C])
+
+          # Restore flags.
+          CPPFLAGS="$CPPFLAGS_SAVED"
+          LDFLAGS="$LDFLAGS_SAVED"
+          LIBS="$LIBS_SAVED"
+          LD_LIBRARY_PATH="$LD_LIBRARY_PATH_SAVED"
+         ])
+
+
+AC_DEFUN([AX_LIB_EVENT],
+         [
+
+          dnl Allow search path to be overridden on the command line.
+          AC_ARG_WITH([libevent],
+                      AS_HELP_STRING([--with-libevent@<:@=DIR@:>@], [use libevent (default is yes) - it is possible to specify an alternate root directory for libevent]),
+                      [
+                       if test "x$withval" = "xno"; then
+                         want_libevent="no"
+                       elif test "x$withval" = "xyes"; then
+                         want_libevent="yes"
+                         ax_libevent_path=""
+                       else
+                         want_libevent="yes"
+                         ax_libevent_path="$withval"
+                       fi
+                       ],
+                       [ want_libevent="yes" ; ax_libevent_path="" ])
+
+
+          if test "$want_libevent" = "yes"; then
+            WANT_LIBEVENT_VERSION=ifelse([$1], ,1.2,$1)
+
+            AC_MSG_CHECKING(for libevent >= $WANT_LIBEVENT_VERSION)
+
+            # Run tests.
+            if test -n "$ax_libevent_path"; then
+              AX_LIB_EVENT_DO_CHECK
+            else
+              for ax_libevent_path in "" /usr /usr/local /opt /opt/local /opt/libevent "$LIBEVENT_ROOT" ; do
+                AX_LIB_EVENT_DO_CHECK
+                if test "$success" = "yes"; then
+                  break;
+                fi
+              done
+            fi
+
+            if test "$success" != "yes" ; then
+              AC_MSG_RESULT(no)
+              LIBEVENT_CPPFLAGS=""
+              LIBEVENT_LDFLAGS=""
+              LIBEVENT_LIBS=""
+            else
+              AC_MSG_RESULT(yes)
+              AC_DEFINE(HAVE_LIBEVENT,,[define if libevent is available])
+            fi
+
+            ax_have_libevent="$success"
+
+            AC_SUBST(LIBEVENT_CPPFLAGS)
+            AC_SUBST(LIBEVENT_LDFLAGS)
+            AC_SUBST(LIBEVENT_LIBS)
+          fi
+
+          ])