[ticket/15295] Restore tests on mysql and myisam

PHPBB3-15295

.travis.yml

@@ -15,7 +15,9 @@ matrix:
     - php: 5.6
       env: DB=mysqli;SLOWTESTS=1
     - php: 5.6
-      env: DB=mysqli
+      env: DB=mysqli # MyISAM
+    - php: 5.6
+      env: DB=mysql
     - php: 7.0
       env: DB=mysqli
     - php: 7.1

travis/setup-database.sh

@@ -26,7 +26,7 @@ then
 	psql -c 'create database phpbb_tests;' -U postgres
 fi
 
-if [ "$TRAVIS_PHP_VERSION" == "5.5" -a "$DB" == "mysqli" ]
+if [ "$TRAVIS_PHP_VERSION" == "5.6" -a "$DB" == "mysqli" ]
 then
 	mysql -e 'SET GLOBAL storage_engine=MyISAM;'
 fi