See thread starting at
<http://lists.gnu.org/archive/html/bug-gnulib/2011-02/msg00161.html>.
Revert previous stdlib change, installing the following instead:
- * lib/stdin.in.h (__attribute__): Remove. We do not want
+ * lib/stdlib.in.h (__attribute__): Remove. We do not want
to get in the way of a non-GCC compiler that supports __attribute__.
(_GL_ATTRIBUTE_RETURN): New macro.
(_Exit): Use it instead of __attribute__.