configure.ac: documentation now needs doxygen

configure.ac

@@ -2160,9 +2160,9 @@ AC_ARG_ENABLE(build-doc, [AS_HELP_STRING([--disable-build-doc],
 			[disable building of documentation])],
 			enable_build_doc=$enableval, enable_build_doc=yes)
 
-# Check whether texi2dvi is installed
-AC_PATH_PROG(texi2dvicommand, texi2dvi)
-if test "$texi2dvicommand" = "" ; then
+# Check whether doxygen is installed
+AC_PATH_PROG(doxygencommand, doxygen)
+if test "$doxygencommand" = "" ; then
 	enable_build_doc="no"
 fi