Allow the Thrift compiler to be built without the Smalltalk generator.

- Use AX_THRIFT_GEN to make configure support --disable-gen-st
- Update the compiler Makefile.am to exclude the generator.


git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@665600 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/configure.ac b/configure.ac
index 862cd53..8e90092 100644
--- a/configure.ac
+++ b/configure.ac
@@ -130,6 +130,8 @@
 AM_CONDITIONAL([THRIFT_GEN_cpp], [test "$ax_thrift_gen_cpp" = "yes"])
 AX_THRIFT_GEN(java, [Java], yes)
 AM_CONDITIONAL([THRIFT_GEN_java], [test "$ax_thrift_gen_java" = "yes"])
+AX_THRIFT_GEN(st, [Smalltalk], yes)
+AM_CONDITIONAL([THRIFT_GEN_st], [test "$ax_thrift_gen_st" = "yes"])
 AX_THRIFT_GEN(ocaml, [OCaml], yes)
 AM_CONDITIONAL([THRIFT_GEN_ocaml], [test "$ax_thrift_gen_ocaml" = "yes"])
 AX_THRIFT_GEN(hs, [Haskell], yes)