Use 'restrict' in all POSIX function declarations. * lib/iconv.in.h (iconv): Use 'restrict'. * lib/inttypes.in.h (strtoimax, strtoumax): Likewise. * lib/monetary.in.h (strfmon_l): Likewise. * lib/pthread.in.h (pthread_create, pthread_mutex_init, pthread_mutexattr_gettype, pthread_mutexattr_getrobust, pthread_mutex_timedlock, pthread_rwlock_init, pthread_rwlock_timedrdlock, pthread_rwlock_timedwrlock, pthread_cond_init, pthread_cond_wait, pthread_cond_timedwait): Likewise. * lib/search.in.h (tdelete): Likewise. * lib/signal.in.h (pthread_sigmask, sigprocmask): Likewise. * lib/stdio.in.h (dprintf, fgets, fopen, fprintf, fputs, fread, freopen, fscanf, fwrite, getdelim, getline, printf, scanf, snprintf, sprintf, vdprintf, vfprintf, vfscanf, vprintf, vscanf, vsnprintf, vsprintf): Likewise. * lib/stdlib.in.h (mbtowc, realpath, strtod, strtold, strtoll, strtoull): Likewise. * lib/string.in.h (strncat): Likewise. * lib/sys_socket.in.h (accept, getpeername, getsockname, getsockopt, recvfrom): Likewise. * lib/sys_stat.in.h (fstatat, lstat, stat): Likewise. * lib/time.in.h (strftime): Likewise. * lib/unistd.in.h (readlink, readlinkat): Likewise. * lib/wchar.in.h (mbrtowc, mbrlen, mbsrtowcs, mbsnrtowcs, wcrtomb, wcsrtombs, wcsnrtombs, wmemcpy, wcscpy, wcpcpy, wcsncpy, wcpncpy, wcscat, wcsncat, wcsxfrm, wcsstr, wcstok, wcsftime): Likewise. * m4/iconv_h.m4 (gl_ICONV_H): Require AC_C_RESTRICT. * m4/inttypes.m4 (gl_INTTYPES_INCOMPLETE): Likewise. * m4/monetary_h.m4 (gl_MONETARY_H): Likewise. * m4/search_h.m4 (gl_SEARCH_H): Likewise. * m4/signal_h.m4 (gl_SIGNAL_H): Likewise. * m4/stdio_h.m4 (gl_STDIO_H): Likewise. * m4/stdlib_h.m4 (gl_STDLIB_H): Likewise. * m4/sys_socket_h.m4 (gl_HEADER_SYS_SOCKET): Likewise. * m4/sys_stat_h.m4 (gl_HEADER_SYS_STAT_H): Likewise. * m4/unistd_h.m4 (gl_UNISTD_H): Likewise. * m4/wchar_h.m4 (gl_WCHAR_H): Likewise. * m4/string_h.m4 (gl_HEADER_STRING_H_BODY): Make consistent with the other *_h.m4 files. * m4/time_h.m4 (gl_HEADER_TIME_H): Likewise.