Fix memory leak in launcher-linux.c

Fix memory leak in launcher-linux.c

When the clientname argument is not a full absolute path we reconstruct
the full path using $PATH. This reconstructed full path would be leaked.
This is small and insignificant. But valgrind should give a good example.
So free the path again when we are done and allocated the memory.
Also don't print the path twice in the debug output if we didn't need to
construct a new different path for it.