disable the 'size_of_tests' on 32-bit architectures (#408)

Author: alexanderkjall

src/lib.rs

@@ -102,7 +102,7 @@ mod parser;
 mod serializer;
 mod unicode_range;
 
-#[cfg(test)]
+#[cfg(all(test,target_pointer_width = "64"))]
 mod size_of_tests;
 #[cfg(test)]
 mod tests;