[ovs-dev] ossfuzz: Add miniflow APIs to fuzz target

[Bhargava Shastry]

Hello,

The attached patch adds miniflow APIs to the flow extract fuzzer target.
Most of the additional code has been adapted from "test-classifier.c".

The patch increases coverage of `lib/flow.c` from 39% to 43%, covers
three additional files and increases coverage in five other
source/header files.

Regards,
Bhargava
-- 
Bhargava Shastry <bshastry at sect.tu-berlin.de>
Security in Telecommunications
TU Berlin / Telekom Innovation Laboratories
Ernst-Reuter-Platz 7, Sekr TEL 17 / D - 10587 Berlin, Germany
phone: +49 30 8353 58235
Keybase: https://keybase.io/bshastry