Update apt-get before trying to install autoconf

Should fix errors with @CircleCI.

circle.yml

@@ -8,6 +8,7 @@ dependencies:
     - "~/erlang"
 
   pre:
+    - sudo apt-get update
     - sudo apt-get install autoconf2.59
     - cd $HOME/bin && ln -s /usr/bin/autoconf2.59 autoconf
     - cd $HOME/bin && ln -s /usr/bin/autoheader2.59 autoheader