[SunOS] PID 0 raises FileNotFoundError

[giampaolo]

From:
#1638 (comment)

======================================================================
ERROR: psutil.tests.test_process.TestProcess.test_pid_0
----------------------------------------------------------------------
Traceback (most recent call last):
  File "<...>/site-packages/psutil/_common.py", line 342, in wrapper
    ret = self._cache[fun]
AttributeError: _cache

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<...>/site-packages/psutil/tests/test_process.py", line 1425, in test_pid_0
    self.assertRaises(psutil.NoSuchProcess, psutil.Process, 0)
  File "<...>/unittest/case.py", line 733, in assertRaises
    return context.handle('assertRaises', args, kwargs)
  File "<...>/unittest/case.py", line 178, in handle
    callable_obj(*args, **kwargs)
  File "<...>/site-packages/psutil/__init__.py", line 446, in __init__
    self._init(pid)
  File "<...>/site-packages/psutil/__init__.py", line 473, in _init
    self.create_time()
  File "<...>/site-packages/psutil/__init__.py", line 823, in create_time
    self._create_time = self._proc.create_time()
  File "<...>/site-packages/psutil/_pssunos.py", line 343, in wrapper
    return fun(self, *args, **kwargs)
  File "<...>/site-packages/psutil/_pssunos.py", line 436, in create_time
    return self._proc_basic_info()[proc_info_map['create_time']]
  File "<...>/site-packages/psutil/_pssunos.py", line 343, in wrapper
    return fun(self, *args, **kwargs)
  File "<...>/site-packages/psutil/_common.py", line 345, in wrapper
    return fun(self)
  File "<...>/site-packages/psutil/_pssunos.py", line 399, in _proc_basic_info
    ret = cext.proc_basic_info(self.pid, self._procfs_path)
FileNotFoundError: [Errno 2] No such file or directory: '/proc/0/psinfo'

Instead we should get AccessDenied.