vim-patch:7.4.543.

Adapt #1533 and #1596 to conform to upstream patch
(https://groups.google.com/forum/#!topic/vim_dev/vp0Lwo9f56s).

Problem:    Since patch 7.4.232 "1,3s/\n//" joins two lines instead of
            three.
            (Eliseo Martínez)  Issue 287
Solution:   Correct the line count. (Christian Brabandt)
            Also set the last used search pattern.
Merge pull request #1666 from elmart/vim-patch-7.4.543

vim-patch:7.4.543.
Remove VMS remnants
Remove dec-mcs remnants

It was (apparently) the default character encoding file used for line
printing on VMS, which is unsupported.
Remove Amiga remnants

Notes regarding the removal of specific items:

  - Aztec C: only on the Amiga.
  - mch_check_win(): doesn't exist anymore.
  - Comment in ex_cmds.c: It seems the context for this comment was
    removed, but the comment was inadvertantly left alone.