[PATCH v1] test/performance: fix IPv4 checksum

[rahul-bhansali]

An issue of incorrect IPv4 checksum is observed when sources are compiled in release mode with optimization flags -fno-var-tracking-assignments. On annotating, it was observed that few IP header fields are updated after checksum calculation routine.

Using this API odph_ipv4_csum_update() solves the issue as it synchronizes the load/store instructions.