iOS Code built with Unity5 with arm64 support gives error in cstring file

I had unity3d code created in Unity 4.3. To support arm64, I imported same code in Unity 5 (Personal Edition). After updating some deprecated function, I was able to make iOS build from it using IL2CPP. The output was a xcode project as usual. I copied files from new code to my existing project and made necessary changes to make it look similar to code exported from Unity 5.

Till here It was working fine, but when I started to build my project, It started showing me multiple errors like following :

/Applications/Xcode 6.2.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/cstring:72:9: No member named ‘strcpy’ in the global namespace

These errors occurs while compiling precompiled headers. Attached some links to screenshots for more information.

Initially, I would suggest that something is wrong with the Xcode installation. Can you build an empty project for iOS 64-bit using IL2CPP? I’m also curious about this step:

I copied files from new code to my existing project and made necessary changes to make it look similar to code exported from Unity 5.

What does this involve? Normally, there should be no need to copy additional files.

Finally, it might be easier to use 4.6.4 as the 4.6 series also supports iOS 64-bit, and might require fewer changes from your project to get from 4.3.