add arm64 architecture support

[agentS]

Although having followed your library build instruction and having run the great library on an old iPhone 4s I am unable to compile the library for usage with a device running a 64 bit ARM processor. Despite of having researched I have not been able to modify the build settings, which are shown in the screenshots below, in order to fit the requirements.

[dbottillo]

same issue here :/

[tciuro]

Please let me know if this works for you.

[dbottillo]

works for me, thank you very much!!!