Fix usage of invalid variables

[CRS-migration-bot]

Issue for tracking original pull request created by user victorhora on date 2018-09-11 21:02:03.
Link to original PR: SpiderLabs/owasp-modsecurity-crs#1187.

HEAD is: 0fe365c0407554679c9040134cb87481f1d4e2ce
BASE is: c06e2f5
MATCHED_VAR_NAMES is an invalid variable with ModSecurity. It should be MATCHED_VARS_NAMES.

This should allow CRS 3.2/dev to load cleanly with the current version of libModSecurity.

Thanks! :)