Dynamic modules: introduced HTTP_INIT_FILTER_MODULES.

Additionally, HTTP_HEADERS_FILTER_MODULE now added to HTTP_FILTER_MODULES.
This avoids explict use of modules at the later stages, now only module
lists are used.  This will be needed in later patches.
diff --git a/auto/modules b/auto/modules
index b2d2ee4..8e2f43b 100644
--- a/auto/modules
+++ b/auto/modules
@@ -185,10 +185,17 @@
     HTTP_SRCS="$HTTP_SRCS $HTTP_USERID_SRCS"
 fi
 
+HTTP_FILTER_MODULES="$HTTP_FILTER_MODULES $HTTP_HEADERS_FILTER_MODULE"
+
+
+HTTP_INIT_FILTER_MODULES="$HTTP_COPY_FILTER_MODULE \
+                          $HTTP_RANGE_BODY_FILTER_MODULE \
+                          $HTTP_NOT_MODIFIED_FILTER_MODULE"
+
 if [ $HTTP_SLICE = YES ]; then
     HTTP_SRCS="$HTTP_SRCS $HTTP_SLICE_SRCS"
-else
-    HTTP_SLICE_FILTER_MODULE=""
+    HTTP_INIT_FILTER_MODULES="$HTTP_INIT_FILTER_MODULES \
+                              $HTTP_SLICE_FILTER_MODULE"
 fi
 
 
@@ -469,12 +476,7 @@
 
 if [ $HTTP = YES ]; then
     modules="$modules $HTTP_MODULES $HTTP_FILTER_MODULES \
-             $HTTP_HEADERS_FILTER_MODULE \
-             $HTTP_AUX_FILTER_MODULES \
-             $HTTP_COPY_FILTER_MODULE \
-             $HTTP_RANGE_BODY_FILTER_MODULE \
-             $HTTP_NOT_MODIFIED_FILTER_MODULE \
-             $HTTP_SLICE_FILTER_MODULE"
+             $HTTP_AUX_FILTER_MODULES $HTTP_INIT_FILTER_MODULES"
 
     NGX_ADDON_DEPS="$NGX_ADDON_DEPS \$(HTTP_DEPS)"
 fi