hush: add support for ':'; create testsuite entries

   text    data     bss     dec     hex filename
 809569     612    7044  817225   c7849 busybox_old
 809528     612    7044  817184   c7820 busybox_unstripped

diff --git a/shell/hush_test/hush-misc/colon.tests b/shell/hush_test/hush-misc/colon.tests
new file mode 100755
index 0000000..ea3b4d5
--- /dev/null
+++ b/shell/hush_test/hush-misc/colon.tests
@@ -0,0 +1,6 @@
+false
+:
+echo $?
+# Extra ; after done is due to a bug
+(while :; do exit; done;)
+echo OK: $?