Added host-building mixer test

Tools/tests-host/mixer_test.cpp

@@ -0,0 +1,12 @@
+#include <systemlib/mixer/mixer.h>
+#include <systemlib/err.h>
+
+extern int test_mixer(int argc, char *argv[]);
+
+int main(int argc, char *argv[]) {
+	warnx("Host execution started");
+
+	char* args[] = {argv[0], "../../ROMFS/px4fmu_common/mixers/IO_pass.mix"};
+
+	test_mixer(2, args);
+}