Fix Asteroid Table Parsing (#7068)

* Zero initialize the string

* Initialize Radius

Author: MjnMixael

code/asteroid/asteroid.cpp

@@ -2488,8 +2488,8 @@ static void asteroid_parse_tbl(const char* filename)
 			Asteroid_impact_explosion_ani = particle::util::parseEffect();
 		}
 		else {
-			char impact_ani_file[MAX_FILENAME_LEN];
-			float Asteroid_impact_explosion_radius;
+			char impact_ani_file[MAX_FILENAME_LEN] = {0};
+			float Asteroid_impact_explosion_radius = 0.0f;
 			int num_frames;
 
 			if (optional_string("$Impact Explosion:")) {