validation: common: return number of threads created
validation: common: return number of threads created

odph_linux_pthread_create() now returns the number of threads created,
so modify odp_cunit_thread_create() to do the same.

Change-Id: I086ac09e2b0ae2dea1b4d777128de8acca5874d1
Signed-off-by: Stuart Haslam <1fce01f364ef5298e64e07a42e08efeef153fa98@linaro.org>
Reviewed-by: Christophe Milard <99616a981fa4477cda708a70f78076761c0c9f1c@linaro.org>

rsalveti/odp,erachmi/odp,erachmi/odp,kalray/odp-mppa,kalray/odp-mppa,mike-holmes-linaro/odp,kalray/odp-mppa,rsalveti/odp,kalray/odp-mppa,mike-holmes-linaro/odp,rsalveti/odp,rsalveti/odp,rsalveti/odp,dkrot/odp,mike-holmes-linaro/odp,dkrot/odp,erachmi/odp,ravineet-singh/odp,kalray/odp-mppa,nmorey/odp,nmorey/odp,kalray/odp-mppa,dkrot/odp,nmorey/odp,ravineet-singh/odp,ravineet-singh/odp,mike-holmes-linaro/odp,erachmi/odp,dkrot/odp,nmorey/odp,ravineet-singh/odp,kalray/odp-mppa