Allow the Thrift compiler to be built without the C++ generator.

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


git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@665516 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/configure.ac b/configure.ac
index 96329ce..13f0d8e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -113,6 +113,9 @@
 AC_CHECK_FUNCS([strtol])
 AC_CHECK_FUNCS([sqrt])
 
+AX_THRIFT_GEN(cpp, [C++], yes)
+AM_CONDITIONAL([THRIFT_GEN_cpp], [test "$ax_thrift_gen_cpp" = "yes"])
+
 AC_CONFIG_HEADERS(config.h:config.hin)
 
 AC_CONFIG_FILES([