Fuchsia: Add native symbol resolver. Small fixes.

runtime/platform/utils_fuchsia.h

 // Copyright (c) 2016, 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.
 
 #ifndef PLATFORM_UTILS_FUCHSIA_H_
 #define PLATFORM_UTILS_FUCHSIA_H_
 
 #include <endian.h>
 
 namespace dart {
@@ skipping 44 matching lines @@
   return htole32(value);
 }
 
 
 inline uint64_t Utils::HostToLittleEndian64(uint64_t value) {
   return htole64(value);
 }
 
 
 inline char* Utils::StrError(int err, char* buffer, size_t bufsize) {
-  snprintf(buffer, bufsize, "errno = %d", err);
+  if (strerror_r(err, buffer, bufsize) != 0) {
+    snprintf(buffer, bufsize, "%s", "strerror_r failed");
+  }
   return buffer;
 }
 
 }  // namespace dart
 
 #endif  // PLATFORM_UTILS_FUCHSIA_H_