include: Add ARM endianess.
diff --git a/include/basetsd.h b/include/basetsd.h
index e106e24..308a65d 100644
--- a/include/basetsd.h
+++ b/include/basetsd.h
@@ -271,6 +271,10 @@
 # undef  WORDS_BIGENDIAN
 # undef  BITFIELDS_BIGENDIAN
 # undef  ALLOW_UNALIGNED_ACCESS
+#elif defined(__arm__)
+# undef  WORDS_BIGENDIAN
+# undef  BITFIELDS_BIGENDIAN
+# undef  ALLOW_UNALIGNED_ACCESS
 #elif !defined(RC_INVOKED) && !defined(__WIDL__) && !defined(__midl)
 # error Unknown CPU architecture!
 #endif