* Move following fields from _PyCoreConfig to _PyPreConfig:
* coerce_c_locale
* coerce_c_locale_warn
* legacy_windows_stdio
* utf8_mode
* _PyPreConfig_ReadFromArgv() is now responsible to choose the
filesystem encoding
* _PyPreConfig_Write() now sets the LC_CTYPE locale
* Add _PyPreConfig structure
* Move 'ignored' and 'use_environment' fields from _PyCoreConfig
to _PyPreConfig
* Add a new "_PyPreConfig preconfig;" field to _PyCoreConfig