remove unneeded checks

examples/models/resources/shaders/glsl100/voxel_lighting.fs

@@ -1,7 +1,6 @@
 #version 100
-#ifdef GL_ES
+
 precision mediump float;
-#endif
 
 // Input from vertex shader
 varying vec3 fragPosition;

examples/models/resources/shaders/glsl100/voxel_lighting.vs

@@ -1,7 +1,6 @@
 #version 100
-#ifdef GL_ES
+
 precision mediump float;
-#endif
 
 // Input vertex attributes
 attribute vec3 vertexPosition;