Allocate a new java.nio.ByteBuffer with allocateDirect

Property definitions

java $ Java_nio_ByteBuffer :: direct
	# Allocate a new `java.nio.ByteBuffer` with `allocateDirect`
	new direct(size: Int) in "Java" `{
		return java.nio.ByteBuffer.allocateDirect((int)size);
	`}
lib/java/ffi_support.nit:288,2--291,3