Remove LOCAL_DATETIME_OFFSET_SECS and LOCAL_DATETIME_OFFSET constants

Also, mark a spec as pending when using the do adapter (except on
SQLite).

lib/sequel/timezones.rb

@@ -1,10 +1,4 @@
 module Sequel
-  # The offset of the current time zone from UTC, in seconds.
-  LOCAL_DATETIME_OFFSET_SECS = Time.now.utc_offset
-
-  # The offset of the current time zone from UTC, as a fraction of a day.
-  LOCAL_DATETIME_OFFSET = respond_to?(:Rational, true) ? Rational(LOCAL_DATETIME_OFFSET_SECS, 60*60*24) : LOCAL_DATETIME_OFFSET_SECS/60/60/24.0
-
   @application_timezone = nil
   @database_timezone = nil
   @typecast_timezone = nil

spec/core/dataset_spec.rb

@@ -3631,7 +3631,7 @@ def @ds.fetch_rows(sql, &block)
     @dataset.literal(t).should == "#{s}#{@offset}'"
 
     t = DateTime.now.new_offset(0)
-    s = t.new_offset(Sequel::LOCAL_DATETIME_OFFSET).strftime("'%Y-%m-%d %H:%M:%S")
+    s = t.new_offset(DateTime.now.offset).strftime("'%Y-%m-%d %H:%M:%S")
     @dataset.literal(t).should == "#{s}#{@offset}'"
   end
 

spec/integration/timezone_test.rb

@@ -54,7 +54,7 @@ def test_timezone
     test_timezone
   end
 
-  specify "should support using local time for both database storage and for application" do
+  cspecify "should support using local time for both database storage and for application", [:do, proc{|db| db.database_type != :sqlite}] do
     Sequel.default_timezone = :local
     test_timezone
   end