Not-set TOOLPREFIX is not fatal on most systems.
Better QEMU autodetection.
Move zombie.c to tests folder.

'Cause it's a test.
Merge pull request #3 from m1kc/qemu-detection

Better QEMU autodetection
Merge pull request #4 from m1kc/move-zombie

Move zombie.c to tests folder
Merge pull request #2 from m1kc/nftp

Не отказываться собираться, если TOOLPREFIX не задан