use c++20 for system_cxx compiler for Windows

b5e7063b51b153a87500929c939726fc517e2c4a

build/ymake_conf.py

@@ -1815,10 +1815,6 @@ class MSVCToolchainOptions(ToolchainOptions):
             sdk_dir = os.environ.get('WindowsSdkDir')
             self.sdk_version = os.environ.get('WindowsSDKVersion').replace('\\', '')
             vc_install_dir = os.environ.get('VCToolsInstallDir')
-            # fix for cxx_std detection problem introduced in r7740071 when running in native VS toolkit commandline:
-            # in that case ya make gets 'system_cxx' configuration name and cxx_std is obviously missing in that config
-            # so default 'c++20' is substituted and we need to hotfix it here
-            self.cxx_std = 'c++latest'
 
             if any([x is None for x in (sdk_dir, self.sdk_version, vc_install_dir)]):
                 raise ConfigureError('No %WindowsSdkDir%, %WindowsSDKVersion% or %VCINSTALLDIR% present. Please, run vcvars64.bat to setup preferred environment.')