BUILD: hlua: include proxy.h from hlua.c

Many proxy functions are called there but the include was missing and
inherited via cfgparse.h.
diff --git a/src/hlua.c b/src/hlua.c
index 328423b..0c0895e 100644
--- a/src/hlua.c
+++ b/src/hlua.c
@@ -45,7 +45,7 @@
 #include <haproxy/obj_type.h>
 #include <haproxy/pattern.h>
 #include <haproxy/payload.h>
-#include <haproxy/proxy-t.h>
+#include <haproxy/proxy.h>
 #include <haproxy/regex.h>
 #include <haproxy/sample.h>
 #include <haproxy/server.h>