isatty: Make it return true in Cygwin consoles on native Windows. * lib/isatty.c: Include <string.h>. (GetProcAddress): New macro. (GetNamedPipeClientProcessIdFuncType): New type. (GetNamedPipeClientProcessIdFunc): New variable. (QueryFullProcessImageNameFuncType): New type. (QueryFullProcessImageNameFunc): New variable. (initialized): New variable. (initialize): New function. (IsCygwinConsoleHandle): New function. (isatty): Invoke it. * doc/posix-functions/isatty.texi: Mention the issue.

#include <sys/types.h>
int dirchownmod (int, char const *, mode_t, uid_t, gid_t, mode_t, mode_t);