[PATCH 3/6] test: fix race condition in ELF load tests

[Marat Khalili]

For the create_temp_bpf_file part I'm not 100% convinced by the explanation. 
Although fsync will not make things worse, it should not be necessary unless 
the infra is broken (but then we'd see other problems; and note that if we 
started to call fsync we also need to call it on directory etc.). Another 
possibility is write call getting interrupted before all data is written. Can 
you share an example of failed job? Can we add more error handling and logging, 
like check return value from close (also fsyncs if we add them)? Can we use 
stdio calls instead of libc ones BTW, they will handle partial writes at least, 
on top of being more portable?

Can ack the port part.

P.S. Did not worth its own patch, but since you are working on it can you also 
do s/sizeof(struct rte_mbuf)/RTE_MBUF_DEFAULT_BUF_SIZE/g ? I overlooked it last 
time.