time.c: DATA_PTR is never NULL

* time.c (time_mark): remove NULL check
  (time_memsize): ditto
  (time_free): remove, use RUBY_TYPED_DEFAULT_FREE instead
  [Feature #10219]

Tiny improvement on my old Phenom II X4 945 system:
$ ruby --disable=gems -e '6000000.times { Time.now }'
before: 2.51user 0.00system 0:02.51elapsed 100%CPU
 after: 2.45user 0.00system 0:02.45elapsed 100%CPU

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47506 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* remove trailing spaces.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47507 b2dd03c8-39d4-4d8f-98ff-823fe69b080e