sim: run: move linking into top-level

Automake will run each subdir individually before moving on to the next
one.  This means that the linking phase, a single threaded process, will
not run in parallel with anything else.  When we have to link ~32 ports,
that's 32 link steps that don't take advantage of parallel systems.  On
my really old 4-core system, this cuts a multi-target build from ~60 sec
to ~30 sec.  We eventually want to move all compile+link steps to this
common dir anyways, so might as well move linking now for a nice speedup.

We use noinst_PROGRAMS instead of bin_PROGRAMS because we're taking care
of the install ourselves rather than letting automake process it.

sim/m32c/local.mk

@@ -16,6 +16,18 @@
 ## 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%_run_SOURCES =
+%C%_run_LDADD = \
+	%D%/main.o \
+	%D%/libsim.a \
+	$(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) -C $(@D) $(@F)
+
 %C%_BUILD_OUTPUTS = \
 	%D%/opc2c$(EXEEXT) \
 	%D%/m32c.c \