Move the functions launching clients to main.c

They belong in the compositor rather than libweston since they
set signals handlers, and a library should not do that behind its
user's back. Besides, they were using functions in main.c already
so they were not usable by other compositors.

Signed-off-by: Giulio Camuffo <giuliocamuffo@gmail.com>
Reviewed-by: Quentin Glidic <sardemff7+git@sardemff7.net>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>

tests/ivi_layout-test-plugin.c

@@ -33,6 +33,7 @@
 #include <assert.h>
 
 #include "src/compositor.h"
+#include "src/weston.h"
 #include "weston-test-server-protocol.h"
 #include "ivi-test.h"
 #include "ivi-shell/ivi-layout-export.h"

tests/weston-test.c

@@ -32,6 +32,7 @@
 #include <string.h>
 
 #include "src/compositor.h"
+#include "src/weston.h"
 #include "weston-test-server-protocol.h"
 
 #ifdef ENABLE_EGL