Replace assert(0) with abort() or cpu_abort()

When building with -DNDEBUG, assert(0) will not stop execution
so it must not be used for abnormal termination.

Use cpu_abort() when in CPU context, abort() otherwise.

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/qdict.c b/qdict.c
index 7fb425a..aae57bf 100644
--- a/qdict.c
+++ b/qdict.c
@@ -194,8 +194,7 @@
     case QTYPE_QINT:
         return qint_get_int(qobject_to_qint(obj));
     default:
-        assert(0);
-        return 0.0;
+        abort();
     }
 }