In build macros, the test in this string: %{?__libtoolize:[ -f configure.in ] && %{__libtoolize} --copy --force ;} should be modified to trigger on configure.ac as well: %{?__libtoolize:[ -f configure.in -o -f configure.ac ] && %{__libtoolize} --copy --force ;}
Fixed in rpm-build-4.0.4-alt26