Fix newline substitution: Adapt to upstream patch.

Fix previous changes to be compatible with agreed changes to upstream
vim (https://code.google.com/p/vim/issues/detail?id=287).
Merge pull request #1596 from elmart/fix-newline-subst

Fix newline substitution: Adapt to upstream patch.
Fix memory leak detected in PR 1510.

LSAN/ASAN detected, on an error code path, that not all elements of a
struct ChannelCallFrame were freed.
Proposed fix by @tarruda for memory leak.
Allow most old tests to pass with nocp
Allow the rest of the old tests to pass with nocp.

Includes the change of one *.ok file that would have otherwise required
cpoptions+=n