[WIP] Add matchaddpos()-related vim patches. [vim-patch: 7.4.330, 7.4.334, 7.4.344, 7.4.362]

Adds patches 7.4.330, 334, 344 and 362.

WARNING: The build passes, but the created executable is unresponsive, for some reason. The error seems to be caused by something in patch 7.4.330. Some help would be appreciated.
Adding this `if` condition around the new code makes the problem go away. No idea if it breaks `matchaddpos`.