gnulib: update

* Makefile.am (gitsort): New.
Use it.

build-aux/.gitignore

@@ -1,6 +1,7 @@
 /announce-gen
 /compile
 /config.guess
+/config.libpath
 /config.rpath
 /config.rpath~
 /config.sub
@@ -11,20 +12,19 @@
 /gitlog-to-changelog
 /gnu-web-doc-update
 /gnupload
+/install-reloc
 /install-sh
 /javacomp.sh.in
 /javaexec.sh.in
+/libtool-reloc
 /mdate-sh
 /missing
 /prefix-gnulib-mk
+/reloc-ldflags
+/relocatable.sh.in
 /test-driver
 /texinfo.tex
 /update-copyright
 /useless-if-before-free
 /vc-list-files
 /ylwrap
-/config.libpath
-/install-reloc
-/reloc-ldflags
-/relocatable.sh.in
-/libtool-reloc