[fuchsia] Use sysconf to get number of processors

runtime/vm/os_fuchsia.cc

 // 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.
 
 #include "vm/globals.h"
 #if defined(TARGET_OS_FUCHSIA)
 
 #include "vm/os.h"
 
 #include <errno.h>
 #include <magenta/syscalls.h>
 #include <magenta/types.h>
-#include <runtime/sysinfo.h>
 
 #include "platform/assert.h"
 #include "vm/zone.h"
 
 namespace dart {
 
 #ifndef PRODUCT
 
 DEFINE_FLAG(bool, generate_perf_events_symbols, false,
     "Generate events symbols for profiling with perf");
@@ skipping 121 matching lines @@
 }
 
 
 bool OS::AllowStackFrameIteratorFromAnotherThread() {
   UNIMPLEMENTED();
   return false;
 }
 
 
 int OS::NumberOfAvailableProcessors() {
-  return mxr_get_nprocs_conf();
+  return sysconf(_SC_NPROCESSORS_CONF);
 }
 
 
 void OS::Sleep(int64_t millis) {
   mx_nanosleep(
       millis * kMicrosecondsPerMillisecond * kNanosecondsPerMicrosecond);
 }
 
 
 void OS::SleepMicros(int64_t micros) {
@@ skipping 137 matching lines @@
 }
 
 
 void OS::Exit(int code) {
   UNIMPLEMENTED();
 }
 
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_FUCHSIA)