mysql_install_db.sh: Fix algorithm for finding pkgdata directory

scripts/mysql_install_db.sh:
  break out of for loop once first valid pkgdata directory is found

scripts/mysql_install_db.sh

@@ -154,6 +154,7 @@ else
     if test -f $i/$fill_help_tables
     then
       pkgdatadir=$i
+      break
     fi
   done