Merge remote-tracking branch 'origin/maint'

* origin/maint:
  maint: update gnu-web-doc-update.
  maint: post-release administrivia
  version 2.6
  maint: prepare for release 2.6
  maint: post-release administrivia
  version 2.5.91
  maint: prepare NEWS.
  maint: fix spaces.
  tests: adjust to case where the C compiler is actually a C++ compiler
  tests: fix dependencies
  doc: fix Texinfo command
  maint: Valgrind on OS X.
  tests: be sure that backups are safe.
  maint: dead comment.
  tests: refactor for legibility.
  tests: refactor the bison invocations.
  maint: fix syntax-check ignore patterns.
  gnulib: update
  gnulib: update.
  gnulib: update

Conflicts:
	build-aux/Makefile.am
	cfg.mk
	tests/Makefile.am

configure.ac

@@ -170,6 +170,16 @@ AC_CONFIG_TESTDIR(tests)
 AC_CONFIG_FILES([tests/atlocal])
 AC_CONFIG_FILES([tests/bison], [chmod +x tests/bison])
 AC_CHECK_PROGS([VALGRIND], [valgrind])
+case $VALGRIND:$host_os in
+  '':*) ;;
+  *:darwin*)
+    # See README-hacking.
+    # VALGRIND+=' --suppressions=$(abs_top_srcdir)/build-aux/darwin11.4.0.valgrind'
+    VALGRIND=;;
+  *:*)
+    AC_SUBST([VALGRIND_PREBISON], [$VALGRIND -q]);;
+esac
+
 AM_MISSING_PROG([AUTOM4TE], [autom4te])
 # Needed by tests/atlocal.in.
 AC_SUBST([GCC])