PHP 7.1 and PHP 7.2: add TEST_TARGET to all extensions
This enables "make test" in every extension and eases
the test of changes to PHP.
I did ignore PHP 7.0 intentionally since it only receives
security updates and will EOL at the end of the year. Therefore
no great amount of work is expected for 7.0.
PHP 7.0 and 7.1: switch to devel/oniguruma6
For mbstring extensions switch from devel/oniguruma5
to devel/oniguruma6 to fix security issues covert in
PHP bundles oniguruma 6.3 but i did some more tests,
to make sure nothing breaks.
Also add $FreeBSD$ header to Makefile.ext
Submitted by: Trond.Endrestol@ximalas.info