Depends-on:
gnulib-local
threadlib
-lock [test x"$glthreads_api" != x"none"]
-tls [test x"$glthreads_api" != x"none"]
+windows-once [test x"$gl_threads_api" = x"windows"]
configure.ac-early:
dnl AC_REQUIRE has the effect of making the macro expansion unconditional;