+ unistd: Avoid #define replacements in C++ mode.
+ * lib/unistd.in.h: Include c++defs.h.
+ (chown, close, dup, dup2, dup3, euidaccess, faccessat, fchdir,
+ fchownat, fsync, ftruncate, getcwd, getdomainname, getdtablesize,
+ getgroups, gethostname, getlogin, getlogin_r, getpagesize,
+ getusershell, setusershell, endusershell, lchown, link, linkat, lseek,
+ pipe2, pread, readlink, readlinkat, rmdir, sleep, symlink, symlinkat,
+ unlink, unlinkat, usleep, write): In C++, define a namespaced alias
+ symbol.
+ (environ): Update.
+ * modules/unistd (Depends-on): Add c++defs.
+ (Makefile.am): Update unistd.h rule.
+