THRIFT-507. Only use Boost for building the C++ library

- Make AX_BOOST_BASE warn instead of fataling if Boost is not found.
- If Boost is not found, disable compilation of the C++ library.
- Do not use CPPFLAGS or LDFLAGS from Boost when building the compiler.

git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@991253 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/configure.ac b/configure.ac
index 838aa94..bee025f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -74,14 +74,14 @@
 AC_PROG_MKDIR_P
 
 AC_LANG([C++])
-AX_BOOST_BASE([1.33.1])
 
 AX_THRIFT_LIB(cpp, [C++], yes)
 have_cpp=no
 if test "$with_cpp" = "yes";  then
-  # Just set this to yes for now, since there is no way
-  # to get through configure without the C++ requirements.
-  have_cpp="yes"
+  AX_BOOST_BASE([1.33.1])
+  if test "x$succeeded" == "xyes" ; then
+    have_cpp="yes"
+  fi
 
   AX_LIB_EVENT([1.0])
   have_libevent=$success