* win32-nat.c (psapi_module_handle): Remove static.

* win32-nat.c (psapi_module_handle): Remove static.
(get_module_name): Rename from psapi_get_dll_name.  Revamp slightly to return
first module found if base_address is zero.  Don't initialize psapi function
pointers here.  Convert to cygwin paths when appropriate.
(win32_pid_to_exec_file): Use Cygwin's /proc interface to determine executable
name.  Use get_module_name when that fails or when !__CYGWIN__.
(_initialize_psapi): New function.  Initialize psapi stuff before it is needed
or issue a warning if it is not found.  Move psapi_module_handle here.