Fix missing shader cache path

platform/android/shader_cache_data.cpp

@@ -0,0 +1,13 @@
+#include <mbgl/platform/platform.hpp>
+#include <mbgl/android/jni.hpp>
+
+namespace mbgl {
+namespace platform {
+
+// Returns the path to the default shader cache on this system.
+std::string defaultShaderCache() {
+    return mbgl::android::cachePath + "/mbgl-shader-cache-";
+}
+
+}
+}