Tool crashes when launching adb when getcwd fails with EACCES.

[zanderso]

Sometimes when launched from an IDE, the tool can crash when the tool process does not have read/list permissions from / up to the cwd.

FileSystemException: FileSystemException: Getting current working directory failed, path = '' (OS Error: Operation not permitted, errno = 1)
  | at _Directory.current | (directory_impl.dart:49)
  | at Directory.current | (directory.dart:161)
  | at LocalFileSystem.currentDirectory | (local_file_system.dart:44)
  | at getExecutablePath | (common.dart:59)
  | at _getExecutable | (local_process_manager.dart:125)
  | at LocalProcessManager.run | (local_process_manager.dart:68)
  | at _DefaultProcessUtils.run | (process.dart:313)
  | at AndroidDevices.pollingGetDevices | (android_device_discovery.dart:54)
  | at PollingDeviceDiscovery._initTimer.<anonymous closure> | (device.dart:295)
  | at _rootRun | (zone.dart:1180)
  | at _CustomZone.run | (zone.dart:1077)
  | at _CustomZone.runGuarded | (zone.dart:979)
  | at _CustomZone.bindCallbackGuarded.<anonymous closure> | (zone.dart:1019)
  | at _rootRun | (zone.dart:1184)
  | at _CustomZone.run | (zone.dart:1077)
  | at _CustomZone.bindCallback.<anonymous closure> | (zone.dart:1003)
  | at Timer._createTimer.<anonymous closure> | (timer_patch.dart:23)
  | at _Timer._runTimers | (timer_impl.dart:398)
  | at _Timer._handleMessage | (timer_impl.dart:429)
  | at _RawReceivePortImpl._handleMessage | (isolate_patch.dart:168)

Supposing that getAdbPath (here) is giving an absolute path, the problem seems to be in package:process, which tries to grab the cwd even though the path might be absolute (here). package:process should probably skip the cwd relative search if grabbing the cwd fails.