[SX-ttinfo.cpp] convert to c++

libgnucash/engine/CMakeLists.txt

@@ -142,7 +142,7 @@ set (engine_SOURCES
   Query.cpp
   SchedXaction.c
   SX-book.cpp
-  SX-ttinfo.c
+  SX-ttinfo.cpp
   Scrub.cpp
   Scrub2.cpp
   Scrub3.cpp

po/POTFILES.in

@@ -692,7 +692,7 @@ libgnucash/engine/ScrubBusiness.c
 libgnucash/engine/Scrub.cpp
 libgnucash/engine/Split.cpp
 libgnucash/engine/SX-book.cpp
-libgnucash/engine/SX-ttinfo.c
+libgnucash/engine/SX-ttinfo.cpp
 libgnucash/engine/Transaction.cpp
 libgnucash/engine/TransLog.cpp
 libgnucash/gnc-module/example/gncmod-example.c