This is equivalent to patches 7.4.396, 7.4.445 and 7.4.598.

vim-patch:7.4.396

Problem:    When 'clipboard' is "unnamed", :g/pat/d is very slow.
(Praful)
Solution:   Only set the clipboard after the last delete. (Christian
Brabandt)

https://github.com/vim/vim/commit/1f285eb49a709e00552f7bef7e74efff5ae79026

vim-patch:7.4.445

Problem:    Clipboard may be cleared on startup.
Solution:   Set clip_did_set_selection to -1 during startup. (Christian
	    Brabandt)

https://github.com/vim/vim/commit/1a19d37d90f037c09183ba68fdddf70ab8ee179a

vim-patch:7.4.598

Problem:    ":tabdo windo echo 'hi'" causes "* register not to be
changed.
	    (Salman Halim)
Solution:   Change how clip_did_set_selection is used and add
	    clipboard_needs_update and global_change_count.  (Christian
	    Brabandt)

https://github.com/vim/vim/commit/af6a579263a688f30bfbbee72b28d08cc7e0f3d4

Co-Author: @bfredl

The test may hang without this.

This occured when clipboard=unnamedplus and doing "+p in visual mode.
Fixes #2942.

This fixes missing clipboard support for `:redir`

Helped-By: Michael Reed <m.reed@mykolab.com>
Helped-By: Scott Prager <splinterofchaos@gmail.com>

When clipboard=unnamed and put over visual selection, reduces number of
provider calls from 6 to 2. Also add test.

Helped-By: Scott Prager <splinterofchaos@gmail.com>

Helped-By: Nicolas Hillegeer <nicolas@hillegeer.com>
Helped-By: Michael Reed <m.reed@mykolab.com>