configure: Don't force a 32-bit build when cross-compiling.
diff --git a/configure.ac b/configure.ac
index d5d8f8e..1a84d69 100644
--- a/configure.ac
+++ b/configure.ac
@@ -101,7 +101,7 @@
 
 case $host in
   x86_64*)
-    if test "x$enable_win64" != "xyes"
+    if test "x$enable_win64" != "xyes" -a "$cross_compiling" != "yes"
     then
       CC="$CC -m32"
       CXX="$CXX -m32"