Testsuite uses CXX to trace mangled symbols.
--- a/configure.ac
+++ b/configure.ac
@@ -53,6 +53,7 @@ AC_SUBST(HOST_CPU)
 
 # Checks for programs.
 AC_PROG_CC
+AC_PROG_CXX
 LT_INIT
 # libtool-2:  LT_INIT()
 AM_INIT_AUTOMAKE([foreign no-exeext dist-bzip2])