sim: rl78: move libsim.a creation to top-level

The objects are still compiled in the subdir, but the creation of the
archive itself is in the top-level.  This is a required step before we
can move compilation itself up, and makes it easier to review.

The downside is that each object compile is a recursive make instead of
a single one.  On my 4 core system, it adds ~100msec to the build per
port, so it's not great, but it shouldn't be a big deal.  This will go
away of course once the top-level compiles objects.

sim/rl78/Makefile.in

@@ -20,15 +20,7 @@
 
 ## COMMON_PRE_CONFIG_FRAG
 
-SIM_RUN_OBJS = \
-	main.o
-
-SIM_OBJS = \
-	load.o \
-	mem.o \
-	cpu.o \
-	rl78.o \
-	gdb-if.o \
-	trace.o
+SIM_LIBSIM =
+SIM_RUN_OBJS =
 
 ## COMMON_POST_CONFIG_FRAG

sim/rl78/local.mk

@@ -16,6 +16,26 @@
 ## You should have received a copy of the GNU General Public License
 ## along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+%C%_libsim_a_SOURCES =
+%C%_libsim_a_LIBADD = \
+	$(common_libcommon_a_OBJECTS) \
+	%D%/load.o \
+	%D%/mem.o \
+	%D%/cpu.o \
+	%D%/rl78.o \
+	%D%/gdb-if.o \
+	%D%/modules.o \
+	%D%/trace.o
+$(%C%_libsim_a_OBJECTS) $(%C%_libsim_a_LIBADD): %D%/hw-config.h
+
+noinst_LIBRARIES += %D%/libsim.a
+
+%D%/%.o: %D%/%.c
+	$(AM_V_at)$(MAKE) $(AM_MAKEFLAGS) -C $(@D) $(@F)
+
+%D%/%.o: common/%.c
+	$(AM_V_at)$(MAKE) $(AM_MAKEFLAGS) -C $(@D) $(@F)
+
 %C%_run_SOURCES =
 %C%_run_LDADD = \
 	%D%/main.o \
@@ -23,7 +43,3 @@
 	$(SIM_COMMON_LIBS)
 
 noinst_PROGRAMS += %D%/run
-
-## Helper targets for running make from the top-level due to run's main.o.
-%D%/%.o: %D%/%.c | %D%/libsim.a $(SIM_ALL_RECURSIVE_DEPS)
-	$(MAKE) $(AM_MAKEFLAGS) -C $(@D) $(@F)