Description: Invoke AC_PROG_CXX, autoreconf fails otherwise.
Forwarded: https://lists.gnu.org/archive/html/bug-plotutils/2016-01/msg00001.html
Author: Floris Bruynooghe <flub@devork.be>

--- a/configure.ac
+++ b/configure.ac
@@ -64,6 +66,7 @@
 # Note: this can apparently alter CFLAGS, on a few platforms, e.g., on
 # SCO OpenServer 5 (i.e. *-*-sco3.2v5*), "-belf" is added.
 AC_PROG_LIBTOOL
+AC_PROG_CXX
 
 # Determine extension (e.g. ".exe") on executables, if any.
 AC_EXEEXT