Libmicrohttpd compatibility

[kripton]

Fix for #1650 : Define a new constant for the return type of functions passed to libmicrohttpd. Also adds some curly braces for ifs and fors that were missing them (code style)

[kripton]

@peternewman : Travis task codespell fails since codespell now seems to require Python >= 3.5

[peternewman]

@peternewman : Travis task codespell fails since codespell now seems to require Python >= 3.5

Yeah that was sorted with the changes I added in #1641 if you fancy cherry-picking them in?

[kripton]

Ah, I see, great :) I've cherry-picked them on top of my changes. Expecting Travis to still fail because of the numpy file collisions. Feel free to merge anyway or find a solution to get Travis back on track :)
The changes I did to get ola to compile with 0.9.70 and 0.9.71 itself are okay I assume?

[peternewman]

LGTM, thanks for doing this!

[peternewman]

The Mac Travis builds are now failing on a new error...

Still not your fault though!

[kripton]

Great :) Feel free to merge this. I'm not allowed due to the Travis build failures.

[peternewman]

Great :) Feel free to merge this.

I was debating what to do about Travis, given it's still bust, and this fixes issues which will block other builds I'm tempted to force merge.

I'm not allowed due to the Travis build failures.

I normally can't during a Travis build failure apart from by some faffing. I don't think you would have the rights to even if Travis is green.

[peternewman]

So I made a bit of progress with Travis on Mac, I can fix the gnupg error, but I then get a different one unfortunately:
#1652

I've got two more things to try, then it will be the nuclear option of just ignoring all the Mac tests for now.

[peternewman]

I take it back @kripton , I've now got a build that works, well it fails at your libmicrohttpd error, so I think it's good. Given the libmicrohttpd error it's a bit of a catch 22. Would you mind pulling in what's in #1652 into this PR, at which point it should go green in Travis and we can merge it?

[kripton]

@peternewman: Well done, Travis doesn't look too bad. Compiles and tests fine on Ubuntu. Test failures on both macOS builds (gcc and clang) are the known, flaky candidates. Can you re-start the Travis build?

[kripton]

I don't get it... now Travis is failing on Ubuntu?

[peternewman]

I don't get it... now Travis is failing on Ubuntu?

😕 It's fine after another go, just waiting for the Mac one to come out green.