added tests as prepared by oliver

test/ref/cc65090910.c

@@ -0,0 +1,26 @@
+/*
+  !!DESCRIPTION!! optimizer bug
+  !!ORIGIN!!      testsuite
+  !!LICENCE!!     Public Domain
+  !!AUTHOR!!      Oliver Schmidt
+*/
+
+/*
+After spending a "little" time I finally succeeded in isolating an
+(maybe THE) optimizer bug causing Contiki to fail.
+
+From my user perspective it is very interesting that the bug shows up
+with compiler option -O but does _not_ show up with -Oi.
+*/
+
+unsigned htons(unsigned val)
+{
+	return (((unsigned) (val)) << 8) | (((unsigned) (val)) >> 8);
+}
+
+int main(void)
+{
+    printf("%x -> %x\n", 0x1234, htons(0x1234) & 0xffff);
+
+    return 0;
+}