Core: enabled "include" inside http upstreams (ticket #635).

The directive already works inside stream upstream blocks.

src/core/ngx_conf_file.h

diff --git a/src/core/ngx_conf_file.h b/src/core/ngx_conf_file.h
index ee44306..2d03f43 100644
--- a/src/core/ngx_conf_file.h
+++ b/src/core/ngx_conf_file.h
@@ -50,7 +50,7 @@
 #define NGX_DIRECT_CONF      0x00010000
 
 #define NGX_MAIN_CONF        0x01000000
-#define NGX_ANY_CONF         0x0F000000
+#define NGX_ANY_CONF         0x1F000000