[fuchsia] Update run_vm_tests_fuchsia for fuchsia launchpad API change

runtime/bin/run_vm_tests_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 <fcntl.h>
 #include <launchpad/launchpad.h>
 #include <magenta/syscalls.h>
 #include <mxio/util.h>
 #include <pthread.h>
 #include <runtime/sysinfo.h>
@@ skipping 138 matching lines @@
   const char* argv[kArgc];
 
   char old_gen_arg[64];
   snprintf(old_gen_arg, sizeof(old_gen_arg), "--old_gen_heap_size=%ld",
       kOldGenHeapSizeMB);
 
   argv[0] = kRunVmTestsPath;
   argv[1] = old_gen_arg;
   argv[2] = test_name;
 
-  mx_handle_t p = launchpad_launch(argv[0], kArgc, argv);
+  mx_handle_t p = launchpad_launch_mxio(argv[0], kArgc, argv);
   if (p < 0) {
     fprintf(stderr, "process failed to start\n");
     return -1;
   }
 
   mx_signals_state_t state;
   mx_status_t r = mx_handle_wait_one(
       p, MX_SIGNAL_SIGNALED, MX_TIME_INFINITE, &state);
   if (r != NO_ERROR) {
     fprintf(stderr, "[process(%x): wait failed? %d]\n", p, r);
@@ skipping 153 matching lines @@
   free(test_list);
   pthread_mutex_destroy(&args_mutex);
 
   if (test_list_index != lines_count) {
     fprintf(stderr, "Failed to attempt all the tests!\n");
     return -1;
   }
 
   return 0;
 }