maint: update to latest gnulib

Among other recent changes, this includes a workaround to avoid
Clang compiler bug https://llvm.org/bugs/show_bug.cgi?id=16404
having spurious link failures.

* .gnulib: Update.
* bootstrap: Synchronize to upstream.
Signed-off-by: NEric Blake <eblake@redhat.com>

.gnulib @ 94386a13

-Subproject commit e210a3cbaec0ee82a67ff8fc427e21bdd64dba1b
+Subproject commit 94386a13667c645fd42544a7fd302cdddd39fcdf

bootstrap

 #! /bin/sh
 # Print a version string.
-scriptversion=2016-11-03.18; # UTC
+scriptversion=2017-01-09.19; # UTC
 
 # Bootstrap this package from checked-out sources.
 
@@ -790,7 +790,7 @@ symlink_to_dir()
       # Leave any existing symlink alone, if it already points to the source,
       # so that broken build tools that care about symlink times
       # aren't confused into doing unnecessary builds.  Conversely, if the
-      # existing symlink's time stamp is older than the source, make it afresh,
+      # existing symlink's timestamp is older than the source, make it afresh,
       # so that broken tools aren't confused into skipping needed builds.  See
       # <http://lists.gnu.org/archive/html/bug-gnulib/2011-05/msg00326.html>.
       test -h "$dst" &&