pythonrun.c: fix Py_GetPythonHome(), use Py_ARRAY_LENGTH() to get the size of
the env_home buffer, not PATH_MAX+1. env_home is declared using MAXPATHLEN+1,
and PATH_MAX is not declared on IRIX.
sysmodule.c: fix sys_update_path(), use Py_ARRAY_LENGTH() to get the size of
the fullpath buffer, not PATH_MAX. fullpath is declared using MAXPATHLEN or
MAX_PATH depending on the OS, and PATH_MAX is not declared on IRIX.
fileutils.c: use MAXPATHLEN instead of PATH_MAX

PATH_MAX is not declared on IRIX nor Windows.
Issue #19523: Closed FileHandler leak which occurred when delay was set.
Issue #19504: Used American spelling for 'customize'.