net: don't fail test if splice fails because pipe2 is missing

This reportedly happens on CentOS 5.11.  The real code will work fine;
this test is assuming that the unexported slice function will handle
the splice, but if pipe2 does not work then it doesn't.  The relevant
code in internal/poll/splice_linux.go says "Falling back to pipe is
possible, but prior to 2.6.29 splice returns -EAGAIN instead of 0 when
the connection is closed."

Change-Id: If48407745c47c677f691d5c0156886eeca5bb9b0
Reviewed-on: https://go-review.googlesource.com/138838
Reviewed-by: Than McIntosh <thanm@google.com>
1 file changed