We can get the same effect using the modules file.
* gl/m4/root-dev-ino.m4: Remove file.
* gl/modules/root-dev-ino (Depends-on): Add lstat.
(Files): Remove m4/root-dev-ino.m4.
(Makefile.am) [lib_SOURCES]: Add root-dev-ino.c and root-dev-ino.h.
(configure.ac): Remove reference to gl_ROOT_DEV_INO.