Remove use of deprecated concatenatePointCloud

[kunaltyagi]

Fixes #3349.

[taketwo]

Is it also possible to locally disable deprecation warnings in test_io.cpp?

[kunaltyagi]

locally disable deprecation warnings

-Wno-deprecated can be applied to a target manually.

[taketwo]

Yes, but AFAIR we create test targets using a CMake macro, so not easy to add a custom option. Can we rather do it in code?

[kunaltyagi]

Can we rather do it in code?

Yes! But it might be compiler dependent. Clang usually respects GCC pragmas, but I don't know about MSVC++.

For more details regarding the following snippet, link

#pragma GCC diagnostic ignored -Wdeprecated
#pragma GCC diagnostic push

... code ...
#pragma diagnostic pop

[taketwo]

I think GCC would be enough, the log in Windows is full of warnings anyway :)

[taketwo]

AppleClang 10 does not seem to like this:

/Users/vsts/agent/2.155.1/work/1/s/test/common/test_io.cpp:133:32: error: expected string literal in pragma diagnostic
#pragma GCC diagnostic ignored -Wdeprecated
                               ^

[kunaltyagi]

Why does Apple have to be so weird? 😆 I'll try somethings and get back later

[taketwo]

Please join the last two commits into one.