ci: Don't use 'native' machine for DPDK cache.

It's possible that actual HW where CI is running is slightly different
between jobs.  That makes all unit tests to fail with cached DPDK
builds due to 'Illegal instruction' crashes.  Changing machine
type to 'default' to generate binaries as generic as possible and avoid
this kind of issues.

Changing the name of a cache version file, so we will not use old
'native' builds that are currently in cache.

Fixes: 7654a3e ("travis: Cache DPDK build.")
Acked-by: Kevin Traynor <ktraynor@redhat.com>
Acked-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

.travis/linux-build.sh

@@ -130,6 +130,10 @@ function install_dpdk()
     sed -i '/CONFIG_RTE_LIBRTE_PMD_PCAP=n/s/=n/=y/' build/.config
     sed -i '/CONFIG_RTE_LIBRTE_PDUMP=n/s/=n/=y/' build/.config
 
+    # Switching to 'default' machine to make dpdk-dir cache usable on different
+    # CPUs.  We can't be sure that all CI machines are exactly same.
+    sed -i '/CONFIG_RTE_MACHINE="native"/s/="native"/="default"/' build/.config
+
     make -j4 CC=gcc EXTRA_CFLAGS='-fPIC'
     EXTRA_OPTS="$EXTRA_OPTS --with-dpdk=$(pwd)/build"
     echo "Installed DPDK source in $(pwd)"