Since v4.13, iproute2 switched to a config.mk file with greater use of
pkg-config for library/feature detection. Replace the old Config patch
with one modifying the configure script but enabling the same changes:
 - explicitly disable TC_CONFIG_ATM
 - rely on feature detection for IP_CONFIG_SETNS and TC_CONFIG_XT

Signed-off-by: Tony Ambardar <itugrok@yahoo.com>