Add a missing munmap_list move constructor

Add a missing munmap_list move constructor

compile_module attempts to request a move constructor, but because
munmap_list doesn't have one it gets implicitly deleted. This is an
warning on clang under -Wdefaulted-function-deleted (which is enabled by
default):

In file included from compile/compile-object-load.c:21:
compile/compile-object-load.h:56:3: error: explicitly defaulted move constructor is implicitly deleted [-Werror,-Wdefaulted-function-deleted]
  compile_module (compile_module &&other) = default;
  ^
compile/compile-object-load.h:86:22: note: move constructor of 'compile_module' is implicitly deleted because field 'munmap_list' has a deleted move constructor
  struct munmap_list munmap_list;
                     ^
compile/compile-object-load.h:30:28: note: 'munmap_list' has been explicitly marked deleted here
  DISABLE_COPY_AND_ASSIGN (munmap_list);
                           ^

gdb/ChangeLog:

	* compile/compile-object-load.h: Give munmap_list a move
	constructor.

Change-Id: I300c52e27da70087f18c7e359773c2b984073d8b