Fix parallel-tests.test failure with HP-UX make

[Ralf Wildenhues]

Now that we know HP-UX make updates files with the same time stamp as
their prerequisites, it is obvious how to fix the long-standing
parallel-tests.test failure.  Pushing to maint as below.

Cheers,
Ralf

    Fix parallel-tests.test failure with HP-UX make.
    
    * tests/parallel-tests.test: Sleep inside inner tests, so logs
    are newer than logs of tests they depend on, for HP-UX make.

diff --git a/tests/parallel-tests.test b/tests/parallel-tests.test
index 29111c2..399b23b 100755
--- a/tests/parallel-tests.test
+++ b/tests/parallel-tests.test
@@ -41,14 +41,19 @@ foo.log: bar.log
 bar.log: baz.log
 END
 
+# foo.test and bar.test sleep to ensure their logs are always strictly newer
+# than the logs of their prerequisites, for HP-UX make.  The quoting pleases
+# maintainer-check.
 cat >>foo.test <<'END'
 #! /bin/sh
 echo "this is $0"
+sleep '1'
 exit 0
 END
 cat >>bar.test <<'END'
 #! /bin/sh
 echo "this is $0"
+sleep '1'
 exit 99
 END
 cat >>baz.test <<'END'