x86: Improve check_stack_align() error message

Make the error more readable and add information about number of
arguments passed on the stack:

  [penberg@tux jruby-1.7.3]$ jato -Xdebug:stack -jar lib/jruby.jar  -v
  Error: stack is 8 bytes misaligned when entering function:

    gnu/java/net/loader/JarURLLoader.<init>(Ljava/net/URLClassLoader;Lgnu/java/net/loader/URLStreamHandlerCache;Ljava/net/URLStreamHandlerFactory;Ljava/net/URL;Ljava/net/URL;)V.

  which has 0 arguments passed on the stack.
  Aborted

Signed-off-by: Pekka Enberg <penberg@kernel.org>