Remove no need binds.empty? checking

[kamipo]

#exec_stmt is private method and only called in #exec_query. it
means binds is provided always. No need binds.empty? checking.

[rails-bot]

r? @sgrif

(@rails-bot has picked a reviewer for you, use r? to override)

[sgrif]

binds is sometimes an empty array

[kamipo]

@sgrif exec_stmt is private method and only called by this line:

https://github.com/kamipo/rails/blob/remove_no_need_binds_empty/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb#L242

      def exec_query(sql, name = 'SQL', binds = [], prepare: false)
        if without_prepared_statement?(binds)
          result_set, affected_rows = exec_without_stmt(sql, name)
        else
          result_set, affected_rows = exec_stmt(sql, name, binds, cache_stmt: prepare)
        end
...

without_prepared_statement? is here:

https://github.com/kamipo/rails/blob/remove_no_need_binds_empty/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb#L525-L527

      def without_prepared_statement?(binds)
        !prepared_statements || binds.empty?
      end

binds is not passed to exec_stmt when it is empty array. What do you think?

[kamipo]

This is follow up to cbcdecd.
We should add !cache_stmt to this line.