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/compiler/cpp/Makefile.am b/compiler/cpp/Makefile.am
index c3bf82e..dacb2a9 100644
--- a/compiler/cpp/Makefile.am
+++ b/compiler/cpp/Makefile.am
@@ -16,7 +16,6 @@
                  src/generate/t_perl_generator.cc \
                  src/generate/t_erl_generator.cc \
                  src/generate/t_cocoa_generator.cc \
-                 src/generate/t_st_generator.cc \
                  src/generate/t_csharp_generator.cc \
                  src/globals.h \
                  src/main.h \
@@ -57,6 +56,9 @@
 if THRIFT_GEN_java
 thrift_SOURCES += src/generate/t_java_generator.cc
 endif
+if THRIFT_GEN_st
+thrift_SOURCES += src/generate/t_st_generator.cc
+endif
 if THRIFT_GEN_ocaml
 thrift_SOURCES += src/generate/t_ocaml_generator.cc
 endif