NetBpfLoad: don't call bpfGetFdMapId in kernels < 4.14

The function is not available in older kernels.

But when we do call it, fail on error - should not happen.

Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I2695bf01762abcbc087a3bd67f1718e0e326576a
1 file changed