#4242 valdiag tests not working

[Philipp Klaus Krause]

I can no longer run the valdiag tests, get error messages like the following (one per target):

Traceback (most recent call last):
  File "/home/philipp/sdcc-trunk/sdcc/support/valdiag/./valdiag.py", line 455, in <module>
    stdoutdata = str(stdoutdata,"utf-8") # convert to str type first
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xf4 in position 329: invalid continuation byte
make[2]: *** [Makefile:59: results/sm83/c2y-ucn-out-of-range.out] Fehler 1
make[1]: *** [Makefile:43: test-port] Fehler 2