option to merge libterminfo objects into libcurses

[staalmannen]

An optional merge of the libterminfo objects into libcurses, and not building libterminfo (perhaps an empty file or symlink should be installed for backwards compatibility?)

Discussed in issue #43

[staalmannen]

Any objections to including the MERGE_TERMINFO option?

[rofl0r]

i've been reluctant merging this as i spent some more thought on it and this change would mean to have 2 abi-incompatible versions of netbsd curses (basically same reason why musl doesn't provide configure option to disable certain functionality) and could provoke a situtation where one tries to file a bug report with an upstream when using the standard ABI, but the upstream could argue "but i tested it with foolinux' netbsd curses install and it worked!".
apart from that, one of the things i criticize about ncurses in the README is exactly the possibility to create various distinct ABI combinations which have led to all the difficulties in correctly detecting the proper C/LDFLAGS for its use.
if i was to merge this, i would do it only as a personal favor, and not out of conviction, which is usually a bad idea in $tech. therefore i'm sorry that i didn't think this through before advising you to come up with a PR.
you're of course welcome to carry the patch in your own distro.

[staalmannen]

Totally fine and good arguments. I will rather then change my behavior downstream in Aalbus. I want to be as "vanilla" as possible and the issues I had with 2 libraries have largely been solved. Totally fine to reject this PR.