maint: remove local maintainer-makefile adjustment

* gl/top/maint.mk.diff: Remove as the fix is now in gnulib.
* gl/local.mk: Remove the diff reference.

gl/local.mk

@@ -81,5 +81,4 @@ gl/modules/targetdir \
 gl/modules/xdectoint \
 gl/modules/xfts \
 gl/tests/test-fadvise.c \
-gl/tests/test-rand-isaac.c \
-gl/top/maint.mk.diff
+gl/tests/test-rand-isaac.c

gl/top/maint.mk.diff

@@ -1,12 +0,0 @@
-diff --git a/top/maint.mk b/top/maint.mk
-index ad60c8fb11..3475f3733c 100644
---- a/top/maint.mk
-+++ b/top/maint.mk
-@@ -1740,6 +1740,7 @@ web-manual:
- 	$(AM_V_GEN)test -z "$(manual_title)" \
- 	  && { echo define manual_title in cfg.mk 1>&2; exit 1; } || :
- 	$(AM_V_at)cd '$(srcdir)/doc'; \
-+	  MAKEINFO="$(MAKEINFO)" \
- 	  $(SHELL) ../$(_build-aux)/gendocs.sh $(gendocs_options_) \
- 	     -o '$(abs_builddir)/doc/manual' \
- 	     --email $(PACKAGE_BUGREPORT) $(PACKAGE) \