GL_EXT_external_buffer
http://www.opengl.org/registry/specs/EXT/external_buffer.txt
GL_EXT_external_buffer

	void glBufferStorageExternalEXT (GLenum target, GLintptr offset, GLsizeiptr size, GLeglClientBufferEXT clientBuffer, GLbitfield flags)
	void glNamedBufferStorageExternalEXT (GLuint buffer, GLintptr offset, GLsizeiptr size, GLeglClientBufferEXT clientBuffer, GLbitfield flags)
	typedef void* GLeglClientBufferEXT