(cwcsdup1): New function.
* cygheap.h (cygheap_user::get_windows_id): New method returning PWCHAR.
(cwcsdup): Declare.
(cwcsdup1): Declare.
* registry.cc (get_registry_hive_path): Use WCHAR instead of char
throughout.
(load_registry_hive): Ditto.
* registry.h (get_registry_hive_path): Change declaration accordingly.
(load_registry_hive): Ditto.
* sec_helper.cc (cygpsid::string): New method returning PWCHAR.
* security.h (cygpsid::string): Declare.
* syscalls.cc (seteuid32): Convert local name var to WCHAR.
* uinfo.cc (cygheap_user::env_userprofile): Convert local name buffers
to WCHAR. Call sys_wcstombs_alloc to generate puserprof buffer.
* winsup.h: Fix comment.
(NT_MAX_PATH): New definition for maximum internal path length.
Use throughout where appropriate.
* include/limits.h (PATH_MAX): Set to 4096 as on Linux.