Removed submodule maplibre-gl-js (#938)

shaders/symbol_icon.fragment.glsl

@@ -0,0 +1,17 @@
+uniform sampler2D u_texture;
+
+varying vec2 v_tex;
+varying float v_fade_opacity;
+
+#pragma mapbox: define lowp float opacity
+
+void main() {
+    #pragma mapbox: initialize lowp float opacity
+
+    lowp float alpha = opacity * v_fade_opacity;
+    gl_FragColor = texture2D(u_texture, v_tex) * alpha;
+
+#ifdef OVERDRAW_INSPECTOR
+    gl_FragColor = vec4(1.0);
+#endif
+}