role-cork: prepare merge with role-ducking: move most code to stream-interaction.c

Filename suggested by Tanu, as it includes both, cork and duck.

src/modules/stream-interaction.h

@@ -0,0 +1,21 @@
+/***
+  This file is part of PulseAudio.
+
+  Copyright 2015 Georg Chini
+
+  PulseAudio is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Lesser General Public License as published
+  by the Free Software Foundation; either version 2.1 of the License,
+  or (at your option) any later version.
+
+  PulseAudio is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with PulseAudio; if not, see <http://www.gnu.org/licenses/>.
+***/
+
+int pa_cork_init(pa_module *m, const char* const v_modargs[]);
+void pa_cork_done(pa_module *m);