cairo: circumvent missing gtkdocize for autoconf 2.70+ (#23971)

var/spack/repos/builtin/packages/cairo/disable-gtk-docs.patch

@@ -0,0 +1,17 @@
+--- autogen.orig.sh	2021-06-08 19:55:17.000000000 -0400
++++ autogen.sh	2021-06-08 19:58:29.000000000 -0400
+@@ -13,13 +13,7 @@
+         exit 1
+ fi
+ 
+-GTKDOCIZE=`which gtkdocize`
+-if test -z $GTKDOCIZE; then
+-        echo "*** No GTK-Doc found, documentation won't be generated ***"
+-else
+-        gtkdocize || exit $?
+-fi
+-
++GTKDOCIZE=echo
+ # create dummy */Makefile.am.features and ChangeLog to make automake happy
+ > boilerplate/Makefile.am.features
+ > src/Makefile.am.features

var/spack/repos/builtin/packages/cairo/package.py

@@ -51,12 +51,13 @@ class Cairo(AutotoolsPackage):
 
     # patch from https://gitlab.freedesktop.org/cairo/cairo/issues/346
     patch('fontconfig.patch', when='@1.16.0:1.17.2')
-
-    def setup_build_environment(self, env):
-        env.set('NOCONFIGURE', "1")
+    # Don't regenerate docs to avoid a dependency on gtk-doc
+    patch('disable-gtk-docs.patch', when='^autoconf@2.70:')
 
     def autoreconf(self, spec, prefix):
-        which('sh')('./autogen.sh')
+        # Regenerate, directing the script *not* to call configure before Spack
+        # does
+        which('sh')('./autogen.sh', extra_env={'NOCONFIGURE': '1'})
 
     def configure_args(self):
         args = [