gdb: remove VALUE_REGNUM, add value::regnum Remove VALUE_REGNUM, replace it with a method on struct value. Set `m_location.reg.regnum` directly from value::allocate_register_lazy, which is fine because allocate_register_lazy is a static creation function for struct value. Change-Id: Id632502357da971617d9dce1e2eab9b56dbcf52d