Remove an unused configure option, and comment that another

seemingly-unused configure option is used by downstream projects.

This commit was SVN r29367.

config/orte_configure_options.m4

@@ -54,6 +54,9 @@ AC_DEFINE_UNQUOTED([ORTE_WANT_ORTERUN_PREFIX_BY_DEFAULT],
 
 #
 # Do we want sensors enabled?
+# Note: this AC_DEFINE is not currently used in the OMPI upstream
+# code, but downstream forked projects are using it.
+#
 
 AC_MSG_CHECKING([if want sensors])
 AC_ARG_ENABLE([sensors],
@@ -70,24 +73,6 @@ AC_DEFINE_UNQUOTED([ORTE_ENABLE_SENSORS],
                    [$orte_want_sensors],
                    [Whether we want sensors enabled])
 
-#
-# Do we want daemon heartbeats enabled?
-
-AC_MSG_CHECKING([if want daemon heartbeats])
-AC_ARG_ENABLE([heartbeat],
-    [AC_HELP_STRING([--enable-heartbeat],
-                    [Enable heartbeat monitoring of daemons (default: disabled)])])
-if test "$enable_heartbeat" = "yes"; then
-    AC_MSG_RESULT([yes])
-    orte_want_heartbeats=1
-else
-    AC_MSG_RESULT([no])
-    orte_want_heartbeats=0
-fi
-AC_DEFINE_UNQUOTED([ORTE_ENABLE_HEARTBEAT],
-                   [$orte_want_heartbeats],
-                   [Whether we want daemon heartbeat monitoring enabled])
-
 AC_MSG_CHECKING([if want orte static ports])
 AC_ARG_ENABLE([orte-static-ports],
               [AC_HELP_STRING([--enable-orte-static-ports],