Upgrade Oniguruma to 6.9.7 revised 1
Summary:
The version is tagged 6.9.7.1 but the archive directory is 6.9.7.
To avoid to maintain two version numbers, this change extracts
the source code to /usr/src/onigurama regardless of the version.
Test Plan: Build image
Reviewers: dereckson
Reviewed By: dereckson
Differential Revision: https://devcentral.nasqueron.org/D2518