Added ax_event_base.m4 to find and configure libevent
Modified configure.ac to pull in AX_EVENT_BASE
Modified Makefile.am to take EVENT settings from automake.

Reviewed by dcorson


git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@664919 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/lib/cpp/Makefile.am b/lib/cpp/Makefile.am
index 771830a..932e802 100644
--- a/lib/cpp/Makefile.am
+++ b/lib/cpp/Makefile.am
@@ -1,7 +1,7 @@
 lib_LTLIBRARIES = libthrift.la
 
-common_cxxflags = -Wall -Isrc $(BOOST_CPPFLAGS)
-common_ldflags = -Wall $(BOOST_LDFLAGS) -levent
+common_cxxflags = -Wall -Isrc $(BOOST_CPPFLAGS) $(EVENT_CPPFLAGS)
+common_ldflags = -Wall $(BOOST_LDFLAGS) $(EVENT_LDFLAGS)
 
 # Define the source file for the module