pf-ring: load plugin by default

Ticket: #7162

configure.ac

@@ -1340,9 +1340,12 @@
 
     if test "x$enable_pfring" = "xyes"; then
         AM_CONDITIONAL([BUILD_PFRING], [true])
+        pfring_comment=""
     else
         AM_CONDITIONAL([BUILD_PFRING], [false])
+        pfring_comment="#"
     fi
+    AC_SUBST([pfring_comment])
 
   # AF_PACKET support
     AC_ARG_ENABLE(af-packet,

suricata.yaml.in

@@ -80,7 +80,8 @@ stats:
 
 # Plugins -- Experimental -- specify the filename for each plugin shared object
 plugins:
-#   - /path/to/plugin.so
+  @pfring_comment@- @prefix@/lib/@PACKAGE_NAME@/pfring.so
+# - /path/to/plugin.so
 
 # Configure the type of alert (and other) logging you would like.
 outputs: