tests: skip nsyscalls-d.test on mips o32

On mips o32, nsyscalls test is implemented using syscall #4000,
so nsyscalls-d cannot work there.

* tests/nsyscalls-d.test: Skip on mips o32.

tests/nsyscalls-d.test

@@ -9,6 +9,8 @@ NAME=nsyscalls-d
 
 if [ "$MIPS_ABI" = "o32" ]; then
 	syscall=syscall
+	[ -z "$debug_flag" ] ||
+		skip_ "mips $MIPS_ABI is not supported by this test yet"
 else
 	syscall=none
 fi