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.

gdb/ChangeLog

@@ -1,3 +1,7 @@
+2018-09-16  Simon Marchi  <simon.marchi@polymtl.ca>
+
+	* Makefile.in (LIBGDB_OBS): Sort COMMON_OBS.
+
 2018-09-16  Tom Tromey  <tom@tromey.com>
 
 	* python/python-internal.h (CPYCHECKER_RETURNS_BORROWED_REF):

gdb/Makefile.in

@@ -1888,7 +1888,7 @@ stamp-init: $(INIT_FILES)
 # against that.
 #
 # init.o is very important.  It pulls in the rest of GDB.
-LIBGDB_OBS = $(COMMON_OBS) init.o
+LIBGDB_OBS = $(sort $(COMMON_OBS)) init.o
 libgdb.a: $(LIBGDB_OBS)
 	-rm -f libgdb.a
 	$(AR) q libgdb.a $(LIBGDB_OBS)

gdb/gdbserver/ChangeLog

@@ -1,3 +1,9 @@
+2018-09-16  Simon Marchi  <simon.marchi@polymtl.ca>
+
+	* Makefile.in (gdbserver$(EXEEXT)): Sort OBS.
+	(gdbreplay$(EXEEXT)): Sort GDBREPLAY_OBS.
+	($(IPA_LIB)): Sort IPA_OBJS.
+
 2018-09-16  Simon Marchi  <simon.marchi@polymtl.ca>
 
 	* Makefile.in: Remove references to $(ADD_DEPS).

gdb/gdbserver/Makefile.in

@@ -395,7 +395,7 @@ install-html:
 clean-info: force
 	@$(MAKE) $(FLAGS_TO_PASS) DO=$@ "DODIRS=$(SUBDIRS)" subdir_do
 
-gdbserver$(EXEEXT): $(OBS) ${CDEPS} $(LIBGNU) $(LIBIBERTY)
+gdbserver$(EXEEXT): $(sort $(OBS)) ${CDEPS} $(LIBGNU) $(LIBIBERTY)
 	$(SILENCE) rm -f gdbserver$(EXEEXT)
 	$(ECHO_CXXLD) $(CC_LD) $(INTERNAL_CFLAGS) $(INTERNAL_LDFLAGS) \
 		-o gdbserver$(EXEEXT) $(OBS) $(LIBGNU) $(LIBIBERTY) \
@@ -406,7 +406,7 @@ all-lib: $(GNULIB_BUILDDIR)/Makefile $(LIBIBERTY_BUILDDIR)/Makefile
 	@$(MAKE) $(FLAGS_TO_PASS) DO=all DODIRS="$(SUBDIRS)" subdir_do
 .PHONY: all-lib
 
-gdbreplay$(EXEEXT): $(GDBREPLAY_OBS) $(LIBGNU) $(LIBIBERTY)
+gdbreplay$(EXEEXT): $(sort $(GDBREPLAY_OBS)) $(LIBGNU) $(LIBIBERTY)
 	$(SILENCE) rm -f gdbreplay$(EXEEXT)
 	$(ECHO_CXXLD) $(CC_LD) $(INTERNAL_CFLAGS) $(INTERNAL_LDFLAGS) \
 		-o gdbreplay$(EXEEXT) $(GDBREPLAY_OBS) $(XM_CLIBS) $(LIBGNU) \
@@ -430,7 +430,7 @@ IPA_OBJS = \
 
 IPA_LIB = libinproctrace.so
 
-$(IPA_LIB): $(IPA_OBJS) ${CDEPS}
+$(IPA_LIB): $(sort $(IPA_OBJS)) ${CDEPS}
 	$(SILENCE) rm -f $(IPA_LIB)
 	$(ECHO_CXXLD) $(CC_LD) -shared -fPIC -Wl,--soname=$(IPA_LIB) \
 		-Wl,--no-undefined $(INTERNAL_CFLAGS) $(INTERNAL_LDFLAGS) \