bodiless.c: Don't write a temporary file in the source directory.

[mattmccutchen-cci]

Hopefully fixes #378 for real this time.

I tested via a temporary chmod u-w clang/test/3C on my laptop that no other tests try to create files in the directory. I assume that result will hold true on Windows too.

[kyleheadley]

So there was just one file left over? How was it missed and how do you know there isn't another one? But feel free to merge this.

[mattmccutchen-cci]

How was it missed

It was the only one that didn't use -output-postfix. I didn't realize there were any tests that wrote to clang/test/3C by other means.

how do you know there isn't another one?

I ran the tests with chmod u-w clang/test/3C. Better ideas?