Fix QEMU restore from file in raw format

Fix QEMU restore from file in raw format

The logic for running the decompression programs was broken in
commit f238709304f9f6c57204cdd943e542cbae38fa5f, so that for
non-raw formats the decompression program was never run, and
for raw formats, it tried to exec an argv[] with initial NULL
in the program name.

* src/qemu/qemu_driver.c: Fix logic in runing decompression program