utimensat: remove FIXME for old Linux kernels * lib/utimensat.c (rpl_utimensat): Update FIXME comment. * m4/utimensat.m4 (gl_FUNC_UTIMENSAT): Belatedy do a "simplify this in 2012" FIXME, by assuming the file system bug is absent unless demonstrated to be present. We no longer need to worry about Linux kernel 2.6.32 when building with newer kernels.