I have this linux multilib peculier patch below to integrate (or  
leave as per-vendor private).

Ralf: What say ye? Integrate or leave as private per-vendor patch?

Index: b/acinclude.m4
===================================================================
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -310,7 +310,7 @@
                          done
                          if test ".${__rcl_found}" = .yes; then
                              __rcl_found=no
-                            for __rcl_dir in ${__rcl_location}/lib/ 
$2 ${__rcl_location}/lib ${__rcl_location}; do
+                            for __rcl_dir in ${__rcl_location}/lib/ 
$2  ${__rcl_location}/lib64/$2 ${__rcl_location}/lib  $ 
{__rcl_location}/lib64 ${__rcl_location}; do
                                  m4_foreach_w([__rcl_lib], [$3], [
                                      if  test -f "${__rcl_dir}/lib[] 
m4_defn([__rcl_lib]).la" && \
                                          test -d "$ 
{__rcl_dir}/.libs"; then

73 de Jeff