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/example-synacor/local.mk

@@ -0,0 +1,25 @@
+## See sim/Makefile.am
+##
+## Copyright (C) 2005-2022 Free Software Foundation, Inc.
+## Written by Mike Frysinger <vapier@gentoo.org>
+##
+## This program is free software; you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 3 of the License, or
+## (at your option) any later version.
+##
+## This program is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+##
+## 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%/nrun.o \
+	%D%/libsim.a \
+	$(SIM_COMMON_LIBS)
+
+noinst_PROGRAMS += %D%/run