win32: get parallel-exec.sh working

The whole suite finishes in under 2 minutes on a 4 CPU VirtualBox
on a macbook. Some tests fail due to incorrect tempdir isolation.

tests/genmakefile.lisp

@@ -0,0 +1,15 @@
+;;;
+;;; invocation: "$SBCL --script genmakefile.lisp >Makefile"
+;;;
+(let ((files (append (directory "*.test.sh")
+                     (directory "*.*pure*.lisp"))))
+  (format t "~%all:")
+  (dolist (file (mapcar 'pathname-name files))
+    (format t " \\~% $(LOGDIR)/~a.log" file))
+  (terpri)
+  (terpri)
+  (dolist (file files)
+    (let ((in (format nil "~a.~a" (pathname-name file) (pathname-type file)))
+          (out (format nil "$(LOGDIR)/~a.log" (pathname-name file))))
+      (format t "~a: ~a~%~a./run-tests.sh ~a >~a 2>&1~%"
+              out in #\tab in out))))

tests/parallel-exec.sh

@@ -5,6 +5,20 @@ echo ==== Writing logs to $logdir ====
 junkdir=${SBCL_PAREXEC_TMP:-/tmp}/junk
 mkdir -p $junkdir $logdir
 
+case `uname` in
+    CYGWIN* | WindowsNT | MINGW* | MSYS*)
+        if [ $# -ne 1 ]
+        then
+            echo $0: Need arg
+            exit 1
+        fi
+        echo ";; Using -j$1"
+        echo "LOGDIR=$logdir" >$logdir/Makefile
+        ../run-sbcl.sh --script genmakefile.lisp >>$logdir/Makefile
+        exec $GNUMAKE -j $1 -f $logdir/Makefile
+        ;;
+esac
+
 export TEST_DIRECTORY SBCL_HOME
 TEST_DIRECTORY=$junkdir SBCL_HOME=../obj/sbcl-home exec ../src/runtime/sbcl \
   --noinform --core ../output/sbcl.core \