Fix build on aarch64

[hfiguiere]

• This is a followup to commit 1ea63cc

This is the patch I used for the flatpak builds of Rawtherapee and Entangle

This does not mean other non-x86_64 builds will work. (it's the only arch with maybe i386 that supports it right now according to the documentation). Ideally this should be checked by checking if the compiler supports it.

[clanmills]

I think we're pursuing a different direction with this issue. @ryandesign is the engineer maintaining Exiv2 on MacPorts and he requested changes to enable the latest code to build on with Xcode 6. #1243

I attempted to use the CMake command CHECK_C_COMPILER_FLAG on every compiler option. Although this makes the CMake code longer, it's simpler. I submitted a PR #1245. Sadly, the PR has numerous errors due my dyslexia. @ryandesign agreed to update the PR. I've set up a Xcode 6.1 on Yosemite to test this for MacPorts.

Can we wait for #1245 to merge and decide the simplest way to deal with your request. Remarkably, I've had requests to support ARM and PPC in the last few weeks and currently have no way to test them. I would very much appreciate help with testing this stuff.

Another important point is that I manage the 0.27-maintenance branch and never submit code to 'master'. If we get this sorted out on 0.27-maintenance, I hope another contributor will port the changes to 'master'.

I'm hoping that 'master' will be released as Exiv2 v0.28 later this year and have offered to be the release engineer for that project. I've received no response to my offer.

[tbeu]

@hfiguiere Can you please confirm that #1252 resolved the issue (for aarch64, too)?

[hfiguiere]

@hfiguiere Can you please confirm that #1252 resolved the issue (for aarch64, too)?

it does. thanks !