THRIFT-781. Install libfb303.so in the correct target lib directory

git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@945318 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/contrib/fb303/cpp/Makefile.am b/contrib/fb303/cpp/Makefile.am
index e62608c..17579c1 100644
--- a/contrib/fb303/cpp/Makefile.am
+++ b/contrib/fb303/cpp/Makefile.am
@@ -58,7 +58,7 @@
 
 # Shared -- multiple libraries can be defined
 if SHARED
-shareddir = lib
+shareddir = $(prefix)/lib
 shared_PROGRAMS = libfb303.so
 libfb303_so_SOURCES = $(fb303_lib)
 libfb303_so_CXXFLAGS = $(SHARED_CXXFLAGS)