perf tools: Fix possible double free on error

Can only be triggered via CROSS_COMPILE env var.

Detected by cppcheck.

Signed-off-by: Thomas Jarosch <thomas.jarosch@intra2net.com>
Link: http://lkml.kernel.org/r/36736865.AIlztKhDqN@storm


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>