Make randomize() use unix time too

(cherry picked from commit 22efa850bd8c10c6f8cc0f99664f660b14c92ffc)

core/math/random_pcg.cpp

@@ -39,7 +39,7 @@ RandomPCG::RandomPCG(uint64_t p_seed, uint64_t p_inc) :
 }
 
 void RandomPCG::randomize() {
-	seed(OS::get_singleton()->get_ticks_usec() * pcg.state + PCG_DEFAULT_INC_64);
+	seed((OS::get_singleton()->get_unix_time() + OS::get_singleton()->get_ticks_usec()) * pcg.state + PCG_DEFAULT_INC_64);
 }
 
 double RandomPCG::random(double p_from, double p_to) {