CLEANUP: tree-wide: Remove any ref to stream-interfaces

Stream-interfaces are gone. Corresponding files can be safely be removed. In
addition, comments are updated accordingly.
diff --git a/src/log.c b/src/log.c
index 5897d2f..36d6d36 100644
--- a/src/log.c
+++ b/src/log.c
@@ -25,7 +25,7 @@
 #include <sys/uio.h>
 
 #include <haproxy/api.h>
-#include <haproxy/applet-t.h>
+#include <haproxy/applet.h>
 #include <haproxy/cfgparse.h>
 #include <haproxy/clock.h>
 #include <haproxy/conn_stream.h>
@@ -42,7 +42,6 @@
 #include <haproxy/sink.h>
 #include <haproxy/ssl_sock.h>
 #include <haproxy/stream.h>
-#include <haproxy/stream_interface.h>
 #include <haproxy/time.h>
 #include <haproxy/tools.h>