Merge pull request #137 from ondys/patch-2

Fixed undefined behavior in BASISU_OFFSETOF
diff --git a/transcoder/basisu.h b/transcoder/basisu.h
index 196d004..6e6f46d 100644
--- a/transcoder/basisu.h
+++ b/transcoder/basisu.h
@@ -88,7 +88,7 @@
 #define BASISU_ARRAY_SIZE(x) (sizeof(x) / sizeof(x[0]))
 #define BASISU_NO_EQUALS_OR_COPY_CONSTRUCT(x) x(const x &) = delete; x& operator= (const x &) = delete;
 #define BASISU_ASSUME(x) static_assert(x, #x);
-#define BASISU_OFFSETOF(s, m) (uint32_t)(intptr_t)(&((s *)(0))->m)
+#define BASISU_OFFSETOF(s, m) offsetof(s, m)
 #define BASISU_STRINGIZE(x) #x
 #define BASISU_STRINGIZE2(x) BASISU_STRINGIZE(x)