Travis: --enable-dba --with-gdbm --tcadb

This PR enables travis tests of ext/dba with the handlers inifile (buildin), flatfile (buildin), cdb (buildin), gdbm and tcadb.

I also would like to add --with-db4 but can't compile :( - see http://travis-ci.org/#!/marc-mabe/php-src/builds/2138877