ClassLoader.java (system): Remove static field.

ClassLoader.java (system): Remove static field.

	* java/lang/ClassLoader.java (system):  Remove static field.
	(getSystemClassLoader):  Get gnu.gcj.runtime.VMClassLoader.instance
	directly instead of using it to set the system field.
	(loadClass):  Use VMClassLoader.instance instead of system field.
	(findSystemClass):   Similar.
	* prims.cc (_Jv_RunMain):  Clear VMClassLoader::instance rather
	than ClassLoader::system which no longer exists.
	* java/lang/natClassLoader.java (_Jv_FindClass):  Simplify.

From-SVN: r45343