Truncation detection in sendfilev() on Solaris.
Truncation detection in sendfilev() on Solaris.

While sendfilev() is documented to return -1 with EINVAL set
if the file was truncated, at least Solaris 11 silently returns 0,
and this results in CPU hog.  Added a test to complain appropriately
if 0 is returned.

hy0kl/nginx,hy0kl/nginx,hy0kl/nginx