I think it's misleading to put #testcases statements further down in
the file because any statements before it will be executed in all
cases. I also find them easier to find at the beginning of the file.
This patch moves the #testcases to the top of the files, which
matches where we have the #requires. I'll leave it to others to move
high-level test file descriptions to before both of these kinds of
statements if they care about that.