Limit YOSYS_MAX_THREADS to 4 for abcopt-tests

Author: rocallahan

tests/aiger/run-test.sh

@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+source ../common-env.sh
 
 set -e
 

tests/alumacc/run-test.sh

@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+source ../common-env.sh
 set -e
 for x in *.ys; do
   echo "Running $x.."

tests/memories/run-test.sh

@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+source ../common-env.sh
 
 set -e