All JDK native libraries needs to have a proper JNI_OnLoad, set either by DEF_STATIC_JNI_OnLoad or DEF_JNI_OnLoad. This is so that in a static build, the JVM can recognize that the library is already loaded, and does not try to load a (non-existent) external library.

Our bundled version of freetype is missing such a marker.

This turns out to be a problem just on Windows, since the ` System.loadLibrary("freetype")` code in FontManagerNativeLibrary is only executed on Windows. However, the cost of including this on the bundled versions on all platforms is very small, and it is a safeguard for any future changes.