chore: support parallel regtests

regtest/runtests.sh

@@ -1,10 +1,27 @@
 #!/usr/bin/env bash
 cd "$(dirname "$0")"
+
+export DVDISASTER_SCSI_SIMULATED_NODELAY=1
+
+if [ "$REGTEST_PARALLEL" = 1 ]; then
+    for i in rs*.bash; do
+       ( RETFILE=/tmp/result.$i REGTEST_NO_UTF8=1 ./$i ) &
+    done
+    wait
+else
+    for i in rs*.bash; do
+       RETFILE=/tmp/result.$i ./$i
+    done
+fi
+
 allfailed=0
 for i in rs*.bash; do
-   ( DVDISASTER_SCSI_SIMULATED_NODELAY=1 ./$i ); ret=$?
+   ret=$(cat /tmp/result.$i)
+   [ -z "$ret" ] && ret=1
+   rm -f /tmp/result.$i
    allfailed=$((allfailed + ret))
 done
+
 echo Failed $allfailed tests
 [ $allfailed -ge 256 ] && allfailed=255
 exit $allfailed