Fix incompatible addition in auto exposure shader

(cherry picked from commit e614a0e9fcaff50c6adc24c5668b96732bc5d89f)

drivers/gles3/shaders/exposure.glsl

@@ -39,7 +39,7 @@ void main() {
 
 #if 1
 	//more precise and expensive, but less jittery
-	ivec2 next_pos = ivec2(gl_FragCoord.xy + ivec2(1)) * source_render_size / target_size;
+	ivec2 next_pos = (ivec2(gl_FragCoord.xy) + ivec2(1)) * source_render_size / target_size;
 	next_pos = max(next_pos, src_pos + ivec2(1)); //so it at least reads one pixel
 	highp vec3 source_color = vec3(0.0);
 	for (int i = src_pos.x; i < next_pos.x; i++) {