Fix module path in the shader templates

src/ol/webgl/shader.mustache

@@ -1,10 +1,10 @@
 // This file is automatically generated, do not edit.
 // Run `make shaders` to generate, and commit the result.
 
-import {DEBUG_WEBGL} from '../../index.js';
+import {DEBUG_WEBGL} from '../../../index.js';
-import _ol_webgl_Fragment_ from '../../webgl/Fragment.js';
+import _ol_webgl_Fragment_ from '../../../webgl/Fragment.js';
-import _ol_webgl_Vertex_ from '../../webgl/Vertex.js';
+import _ol_webgl_Vertex_ from '../../../webgl/Vertex.js';
-var {{namespace}} = {};
+const {{namespace}} = {};
 
 {{namespace}}.fragment = new _ol_webgl_Fragment_(DEBUG_WEBGL ?
   'precision mediump float;\n{{{originalFragmentSource}}}' :

src/ol/webgl/shaderlocations.mustache

@@ -1,7 +1,7 @@
 // This file is automatically generated, do not edit
 // Run `make shaders` to generate, and commit the result.
 
-import {DEBUG_WEBGL} from '../../../index.js';
+import {DEBUG_WEBGL} from '../../../../index.js';
 
 /**
  * @constructor
@@ -9,7 +9,7 @@ import {DEBUG_WEBGL} from '../../../index.js';
  * @param {WebGLProgram} program Program.
  * @struct
  */
-{{namespace}}_Locations_ = function(gl, program) {
+const {{namespace}}Locations_ = function(gl, program) {
 {{#uniforms}}
 
   /**
@@ -28,4 +28,4 @@ import {DEBUG_WEBGL} from '../../../index.js';
 {{/attributes}}
 };
 
-export default {{namespace}}_Locations_;
+export default {{namespace}}Locations_;