remove double import

Imported both inside and outside of T.TYPE_CHECKING, the runtime import
can be removed by quote-deferring one of the use sites.

Update:

In between then and now, this got removed from T.TYPE_CHECKING, move it
back there rather than preserving the runtime import.

mesonbuild/cmake/executor.py

@@ -23,11 +23,11 @@ import re
 import os
 
 from .. import mlog
-from ..environment import Environment
 from ..mesonlib import PerMachine, Popen_safe, version_compare, MachineChoice, is_windows, OptionKey
 from ..programs import find_external_program, NonExistingExternalProgram
 
 if T.TYPE_CHECKING:
+    from ..environment import Environment
     from ..programs import ExternalProgram
 
 TYPE_result    = T.Tuple[int, T.Optional[str], T.Optional[str]]
@@ -65,7 +65,7 @@ class CMakeExecutor:
         if self.prefix_paths:
             self.extra_cmake_args += ['-DCMAKE_PREFIX_PATH={}'.format(';'.join(self.prefix_paths))]
 
-    def find_cmake_binary(self, environment: Environment, silent: bool = False) -> T.Tuple[T.Optional['ExternalProgram'], T.Optional[str]]:
+    def find_cmake_binary(self, environment: 'Environment', silent: bool = False) -> T.Tuple[T.Optional['ExternalProgram'], T.Optional[str]]:
         # Only search for CMake the first time and store the result in the class
         # definition
         if isinstance(CMakeExecutor.class_cmakebin[self.for_machine], NonExistingExternalProgram):