THRIFT-646. erl: Erlang library is missing install target

This patch adds a new install target to the erlang makefile. It also converts the Makefile to Makefile.am

Patch: Anthony Molinaro

git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@940326 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/configure.ac b/configure.ac
index 205cd13..cc71f53 100644
--- a/configure.ac
+++ b/configure.ac
@@ -259,6 +259,7 @@
   lib/cpp/thrift-nb.pc
   lib/cpp/thrift-z.pc
   lib/csharp/Makefile
+  lib/erl/Makefile
   lib/java/Makefile
   lib/perl/Makefile
   lib/perl/test/Makefile