cleanup old folders in ci | add coursier cache export

.circleci/install-verilator.sh

@@ -9,7 +9,9 @@ set -ex
 SCRIPT_DIR="$( cd "$( dirname "$0" )" && pwd )"
 source $SCRIPT_DIR/defaults.sh
 
+# clean older directories (delete prior directories related to this branch also)
 run_script $LOCAL_CHIPYARD_DIR/.circleci/clean-old-files.sh $CI_DIR
+run "rm -rf $REMOTE_PREFIX*"
 
 # set stricthostkeychecking to no (must happen before rsync)
 run "echo \"Ping $SERVER\""
@@ -20,4 +22,4 @@ run "git clone http://git.veripool.org/git/verilator $REMOTE_VERILATOR_DIR; \
      autoconf; \
      export VERILATOR_ROOT=$REMOTE_VERILATOR_DIR; \
      ./configure; \
-     make -j$NPROC;"
+     make -j$REMOTE_MAKE_NPROC;"