tests: Add more items to .gitignore
This patch adds the system* testsuite directory and logs to .gitignore.
Acked-by: Ben Pfaff
/ovs-pki.log
/pki/
/system-dpdk-testsuite
+/system-dpdk-testsuite.dir/
+/system-dpdk-testsuite.log
/system-kmod-testsuite
+/system-kmod-testsuite.dir/
+/system-kmod-testsuite.log
/system-userspace-testsuite
+/system-userspace-testsuite.dir/
+/system-userspace-testsuite.log
/system-offloads-testsuite
+/system-offloads-testsuite.dir/
+/system-offloads-testsuite.log
/test-aes128
/test-atomic
/test-bundle
