tlmu:modified cpu_openrisc_pic_init() to return qemu_irq. and its declaration is moved from cpu.h to openrisc_pic.h (newfile).
tlmu:add openrisc for tlm_mach. loading big-endian elf binary is also supported.
tlmu:add openrisc for tlmu test (c_example)
tlmu:add partial support of endian conversion for big-endian targets.