Add protection for setLocalRoutesExcludedForVpn

setLocalRoutesExcludedForVpn() was added in T for local route
exclusion in VPN. It relies on the behavior change in netd which
is inside platform and will not be updated with mainline update.

Add protection on setLocalRoutesExcludedForVpn to prevent the
API misused on SDK before T.

Bug: 223356811
Test: atest FrameworksNetTests
Change-Id: Ic2927f5c335ddd0c3defd4c377542ce6907ab435
1 file changed