maint: sort .gitignore

Fallout from the new bootstrap.

* .gitignore: Commit sorting done by bootstrap.
* build-aux/.gitignore: Likewise.
* po/.gitignore: Likewise.

.gitignore

@@ -1,13 +1,21 @@
+*#*#
+*.#*#
 *.a
 *.o
+*.orig
+*.rej
 *~
 .git
 .git-module-status
+/GNUmakefile
+/maint.mk
 ABOUT-NLS
 COPYING
+ChangeLog
 INSTALL
 Makefile
 Makefile.in
+NEWS
 aclocal.m4
 autom4te.cache
 config.cache
@@ -22,6 +30,7 @@ configure
 coverage
 cscope.files
 cscope.out
+gnulib/
 libtool
 libvirt-*.tar.gz
 libvirt.pc
@@ -34,14 +43,5 @@ results.log
 stamp-h
 stamp-h.in
 stamp-h1
-update.log
 tests/*.log
-/GNUmakefile
-/maint.mk
-gnulib/
-*.orig
-*.rej
-*#*#
-*.#*#
-ChangeLog
-NEWS
+update.log