$OpenBSD: patch-Makefile_in,v 1.1 2021/01/10 16:10:37 sthen Exp $

even if doxygen is detected, ref docs are not built automatically,
but the install target still tries to install them. just skip the
dir to avoid a problem in install.

Index: Makefile.in
--- Makefile.in.orig
+++ Makefile.in
@@ -410,7 +410,7 @@ top_build_prefix = @top_build_prefix@
 top_builddir = @top_builddir@
 top_srcdir = @top_srcdir@
 ACLOCAL_AMFLAGS = -I m4
-SUBDIRS = data libqalculate src man po po-defs docs
+SUBDIRS = data libqalculate src man po po-defs
 EXTRA_DIST = config.rpath  \
 	autogen.sh \
 	README.translate \
