Sort objects in gdb and gdbserver Makefiles

Sort objects in gdb and gdbserver Makefiles

Tom mentioned this a while ago, as a way to give you a cheap sense of
progression in your build, as all object files will be built
alphabetically (including the directory part).  I tried it and I think
it's nice.

gdb/ChangeLog:

	* Makefile.in (LIBGDB_OBS): Sort COMMON_OBS.

gdb/gdbserver/ChangeLog:

	* Makefile.in (gdbserver$(EXEEXT)): Sort OBS.
	(gdbreplay$(EXEEXT)): Sort GDBREPLAY_OBS.
	($(IPA_LIB)): Sort IPA_OBJS.