build: Fix libevent linking for bench_bitcoin binary

configure.ac

@@ -1255,7 +1255,7 @@ if test x$use_pkgconfig = xyes; then
       if test x$use_qr != xno; then
         BITCOIN_QT_CHECK([PKG_CHECK_MODULES([QR], [libqrencode], [have_qrencode=yes], [have_qrencode=no])])
       fi
-      if test x$build_bitcoin_cli$build_bitcoind$bitcoin_enable_qt$use_tests != xnononono; then
+      if test x$build_bitcoin_cli$build_bitcoind$bitcoin_enable_qt$use_tests$use_bench != xnonononono; then
         PKG_CHECK_MODULES([EVENT], [libevent],, [AC_MSG_ERROR(libevent not found.)])
         if test x$TARGET_OS != xwindows; then
           PKG_CHECK_MODULES([EVENT_PTHREADS], [libevent_pthreads],, [AC_MSG_ERROR(libevent_pthreads not found.)])
@@ -1275,7 +1275,7 @@ if test x$use_pkgconfig = xyes; then
   )
 else
 
-  if test x$build_bitcoin_cli$build_bitcoind$bitcoin_enable_qt$use_tests != xnononono; then
+  if test x$build_bitcoin_cli$build_bitcoind$bitcoin_enable_qt$use_tests$use_bench != xnonononono; then
     AC_CHECK_HEADER([event2/event.h],, AC_MSG_ERROR(libevent headers missing),)
     AC_CHECK_LIB([event],[main],EVENT_LIBS=-levent,AC_MSG_ERROR(libevent missing))
     if test x$TARGET_OS != xwindows; then