only define ARRAYSIZE_UNSAFE for NaCl builds

src/base/macros.h

Index: src/base/macros.h
diff --git a/src/base/macros.h b/src/base/macros.h
index 79cf04ccf2b2637a0c70234ac49849b27e22f20b..752061258adf396f43c511d0c3838c947c3c68be 100644
--- a/src/base/macros.h
+++ b/src/base/macros.h
@@ -25,6 +25,8 @@
   (reinterpret_cast<intptr_t>(&(reinterpret_cast<type*>(4)->field)) - 4)
 
 
+#if V8_OS_NACL
+
 // ARRAYSIZE_UNSAFE performs essentially the same calculation as arraysize,
 // but can be used on anonymous types or types defined inside
 // functions.  It's less safe than arraysize as it accepts some
@@ -65,9 +67,6 @@
   ((sizeof(a) / sizeof(*(a))) / \
    static_cast<size_t>(!(sizeof(a) % sizeof(*(a)))))  // NOLINT
 
-
-#if V8_OS_NACL
-
 // TODO(bmeurer): For some reason, the NaCl toolchain cannot handle the correct
 // definition of arraysize() below, so we have to use the unsafe version for
 // now.