Fix compiler warning: variable 'kill_message' set but not used

kill_message is unused since:

Author:      MRprusa3d <martin.remis@prusa3d.cz>
Date:        4 months ago (11/2/2018 11:03:14 PM)
Commit hash: 73794b56cf532cb4193a6c80082652351509677a

MeshBed Leveling Fail

Z-leveling after MeshBed leveling failing

Firmware/Marlin_main.cpp

@@ -4461,7 +4461,7 @@ if((eSoundMode==e_SOUND_MODE_LOUD)||(eSoundMode==e_SOUND_MODE_ONCE))
 		}
 		#endif // SUPPORT_VERBOSITY
 		int l_feedmultiply = setup_for_endstop_move(false); //save feedrate and feedmultiply, sets feedmultiply to 100
-		const char *kill_message = NULL;
+
 		while (mesh_point != nMeasPoints * nMeasPoints) {
 			// Get coords of a measuring point.
 			uint8_t ix = mesh_point % nMeasPoints; // from 0 to MESH_NUM_X_POINTS - 1
@@ -4511,15 +4511,15 @@ if((eSoundMode==e_SOUND_MODE_LOUD)||(eSoundMode==e_SOUND_MODE_ONCE))
 			// Go down until endstop is hit
 			const float Z_CALIBRATION_THRESHOLD = 1.f;
 			if (!find_bed_induction_sensor_point_z((has_z && mesh_point > 0) ? z0 - Z_CALIBRATION_THRESHOLD : -10.f, nProbeRetry)) { //if we have data from z calibration max allowed difference is 1mm for each point, if we dont have data max difference is 10mm from initial point  
-				kill_message = _T(MSG_BED_LEVELING_FAILED_POINT_LOW);
+				//Bed leveling failed. Sensor didnt trigger. Debris on nozzle?
 				break;
 			}
 			if (MESH_HOME_Z_SEARCH - current_position[Z_AXIS] < 0.1f) {
-				kill_message = _i("Bed leveling failed. Sensor disconnected or cable broken. Waiting for reset.");////MSG_BED_LEVELING_FAILED_PROBE_DISCONNECTED c=20 r=4
+				//Bed leveling failed. Sensor disconnected or cable broken.
 				break;
 			}
 			if (has_z && fabs(z0 - current_position[Z_AXIS]) > Z_CALIBRATION_THRESHOLD) { //if we have data from z calibration, max. allowed difference is 1mm for each point
-				kill_message = _i("Bed leveling failed. Sensor triggered too high. Waiting for reset.");////MSG_BED_LEVELING_FAILED_POINT_HIGH c=20 r=4
+				//Bed leveling failed. Sensor triggered too high.
 				break;
 			}
 			#ifdef SUPPORT_VERBOSITY