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.

#ifndef IDCACHE_H
# define IDCACHE_H 1

# include <sys/types.h>

extern char *getuser (uid_t uid);
extern char *getgroup (gid_t gid);
extern uid_t *getuidbyname (const char *user);
extern gid_t *getgidbyname (const char *group);

#endif