use real pathlib module

We added the _pathlib module to work around defeciencies in python 3.5's
implementation, since we now rely on 3.6 lets drop this

Author: dcbaker

meson.py

@@ -15,7 +15,7 @@
 # limitations under the License.
 
 import sys
-from mesonbuild._pathlib import Path
+from pathlib import Path
 
 # If we're run uninstalled, add the script directory to sys.path to ensure that
 # we always import the correct mesonbuild modules even if PYTHONPATH is mangled

mesonbuild/_pathlib.py

@@ -14,7 +14,7 @@
 
 from collections import OrderedDict
 from functools import lru_cache
-from .._pathlib import Path
+from pathlib import Path
 import enum
 import json
 import os

mesonbuild/backend/backends.py

@@ -20,7 +20,7 @@
 from collections import OrderedDict
 from enum import Enum, unique
 import itertools
-from .._pathlib import PurePath, Path
+from pathlib import PurePath, Path
 from functools import lru_cache
 
 from . import backends

mesonbuild/backend/ninjabackend.py

@@ -19,7 +19,7 @@
 import xml.etree.ElementTree as ET
 import uuid
 import typing as T
-from .._pathlib import Path, PurePath
+from pathlib import Path, PurePath
 
 from . import backends
 from .. import build

mesonbuild/backend/vs2010backend.py

@@ -19,7 +19,7 @@
 from .. import mlog
 from contextlib import contextmanager
 from subprocess import Popen, PIPE, TimeoutExpired
-from .._pathlib import Path
+from pathlib import Path
 import typing as T
 import json
 

mesonbuild/cmake/client.py

@@ -17,7 +17,7 @@
 
 from ..mesonlib import MesonException
 from .. import mlog
-from .._pathlib import Path
+from pathlib import Path
 import typing as T
 
 language_map = {

mesonbuild/cmake/common.py

@@ -16,7 +16,7 @@
 # or an interpreter-based tool.
 
 import subprocess as S
-from .._pathlib import Path
+from pathlib import Path
 from threading import Thread
 import typing as T
 import re

mesonbuild/cmake/executor.py

@@ -15,7 +15,7 @@
 from .common import CMakeException, CMakeBuildFile, CMakeConfiguration
 import typing as T
 from .. import mlog
-from .._pathlib import Path
+from pathlib import Path
 import json
 import re
 

mesonbuild/cmake/fileapi.py

@@ -27,7 +27,7 @@
 from ..compilers.compilers import lang_suffixes, header_suffixes, obj_suffixes, lib_suffixes, is_header
 from enum import Enum
 from functools import lru_cache
-from .._pathlib import Path
+from pathlib import Path
 import typing as T
 import re
 from os import environ