Use ?nullNamePatternMatchesAll=true with mysql 6.0.6

Bug: Issue 7331
Change-Id: I69ad0dd126df23680b7381252ce859c35da56ac7

gerrit-server/src/main/java/com/google/gerrit/server/schema/MySql.java

@@ -41,6 +41,8 @@ class MySql extends BaseDataSourceType {
     b.append(port(dbs.optional("port")));
     b.append("/");
     b.append(dbs.required("database"));
+    // See https://stackoverflow.com/questions/42084633/table-name-pattern-can-not-be-null-or-empty-in-java
+    b.append("?nullNamePatternMatchesAll=true");
     return b.toString();
   }