Pcut creates temporary files in the working directory

[jxsvoboda]

Pcut creates temporary files in the current directory with its homebrew code, either in generic.c or helenos.c. On HelenOS if / is full or if the test is run with WD set to a non-writable directory (e.g. /loc), PCUT will fail to create temporary file for every test.

Suggestion: How about tmpfile() on HelenOS and tmpnam() on generic?