tests: Fix warnings found on Mac.

test_pbx used raise without explicitly including signal.h.  On Mac for
some reason nothing else includes it.

test_logger checked if an unsigned int was negative.  Switch the
variable to 'int' so that error check can be effective.

Change-Id: Ie1db5dd1818ac25cc2ae41b644f848b5865b1362

tests/test_pbx.c

@@ -37,6 +37,8 @@
 #include "asterisk/pbx.h"
 #include "asterisk/test.h"
 
+#include <signal.h>
+
 /*!
  * If we determine that we really need
  * to be able to register more than 10