servo: Support autoconf's named autoconf-2.13

Source-Repo: https://github.com/servo/servo
Source-Revision: be681d85b0c04a40ffba26e2e2b38ad93cea41cf

servo/autogen.sh

@@ -12,6 +12,11 @@ then
     AUTOCONF213=autoconf2.13
 fi
 
+if [ ! -z `which autoconf-2.13` ]
+then
+    AUTOCONF213=autoconf-2.13
+fi
+
 if [ -z "$AUTOCONF213" ]
 then
     echo "I need autoconf 2.13"