Don't check against __BYTE_ORDER__ when not defined.

runtime/vm/regexp.cc

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/regexp.h"
 
 #include "vm/dart_entry.h"
 #include "vm/regexp_assembler.h"
 #include "vm/regexp_ast.h"
 #include "vm/unibrow-inl.h"
@@ skipping 1789 matching lines @@
 //
 // We iterate along the text object, building up for each character a
 // mask and value that can be used to test for a quick failure to match.
 // The masks and values for the positions will be combined into a single
 // machine word for the current character width in order to be used in
 // generating a quick check.
 void TextNode::GetQuickCheckDetails(QuickCheckDetails* details,
                                     RegExpCompiler* compiler,
                                     intptr_t characters_filled_in,
                                     bool not_at_start) {
-#if defined(__GNUC__)
+#if defined(__GNUC__) && defined(__BYTE_ORDER__)
   // TODO(zerny): Make the combination code byte-order independent.
   ASSERT(details->characters() == 1 ||
          (__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__));
 #endif
   ASSERT(characters_filled_in < details->characters());
   intptr_t characters = details->characters();
   intptr_t char_mask;
   if (compiler->one_byte()) {
     char_mask = Symbols::kMaxOneCharCodeSymbol;
   } else {
@@ skipping 3339 matching lines @@
   CreateSpecializedFunction(isolate, regexp, kOneByteStringCid, owner);
   CreateSpecializedFunction(isolate, regexp, kTwoByteStringCid, owner);
   CreateSpecializedFunction(isolate, regexp, kExternalOneByteStringCid, owner);
   CreateSpecializedFunction(isolate, regexp, kExternalTwoByteStringCid, owner);
 
   return regexp.raw();
 }
 
 
 }  // namespace dart