Simplify database_connection_url

* does not expects dynamic scoping.
* does not uses eval.

Change-Id: I5ba4e5b7ffaabbb3c2bddadf9e53a2875de8b7c0
diff --git a/lib/databases/mysql b/lib/databases/mysql
index 94aedc6..ec65c36 100644
--- a/lib/databases/mysql
+++ b/lib/databases/mysql
@@ -115,9 +115,8 @@
 }
 
 function database_connection_url_mysql {
-    local output=$1
-    local db=$2
-    eval "$output=$BASE_SQL_CONN/$db?charset=utf8"
+    local db=$1
+    echo "$BASE_SQL_CONN/$db?charset=utf8"
 }
 
 # Restore xtrace