hush testsuite: add many tests from ash testsuite

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

shell/hush_test/hush-misc/last_amp.tests

@@ -0,0 +1,8 @@
+$THIS_SH -c 'echo 3&'
+d=`date`
+while test "`date`" = "$d"; do true; done
+d1=`date`
+$THIS_SH -c 'sleep 1&'
+d2=`date`
+test "$d1" = "$d2" || echo BAD
+echo End