Use a single = instead of ==

test in the bourne shell and its derivatives actually specifies
= as the test for equality. == was accepted for a long time. But
dash does not. configure2 used == for a test. Which caused debian
to break if dash is used. This changes it to =.

configure2

@@ -149,7 +149,7 @@ cat > config.h << EOF
 /* Automatically generated by configure, do not edit */
 #include "version.h"
 EOF
-test "$bigendian" == "yes" && echo "#define WORDS_BIGENDIAN" || echo "#undef WORDS_BIGENDIAN" >> config.h
+test "$bigendian" = "yes" && echo "#define WORDS_BIGENDIAN" || echo "#undef WORDS_BIGENDIAN" >> config.h
 
 # build tree in object directory if source path is different from current one
 if test "$source_path_used" != "no"; then