Makefile: Don't include transaction.hpp if enable_transaction=no

Change-Id: I1f19ff55a04d44e0fcc1773fb0984067be1edf55
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/Makefile.am b/Makefile.am
index 16a8b3d..037640c 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -16,7 +16,6 @@
 	sdbusplus/server/interface.hpp \
 	sdbusplus/server/manager.hpp \
 	sdbusplus/server/object.hpp \
-	sdbusplus/server/transaction.hpp \
 	sdbusplus/slot.hpp \
 	sdbusplus/utility/tuple_to_array.hpp \
 	sdbusplus/utility/type_traits.hpp \
@@ -26,6 +25,8 @@
 	sdbusplus/exception.cpp
 
 if WANT_TRANSACTION
+nobase_include_HEADERS += \
+	sdbusplus/server/transaction.hpp
 LIBSDBUPLUS_FILES_TRANSACTION = \
 	sdbusplus/server/transaction.cpp
 endif