Use C++ compiler to check for symbols

[smithsg84]

Symbol existence checks changed to use C++ compiler rather than the C compiler

check_symbol_exists use the C compiler for the symbol check, check_cxx_symbol_exists is the C++ variant. The C check was being used to check for a C++ symbol name (std::aligned_alloc) which was failing. Other checks were refactored to use C++ checks since use is in C++ code.

• This PR is a bugfix

[davidbeckingsale]

Very nice - I think we've had similar issues in Umpire.

[smithsg84]

The first choice for aligned allocation is currently posix_memalign. Since RAJA now requires C++ 17 should the first selection be std::aligned_alloc which is in C++17? Remove RAJA wrapper entirely and use standard directly since we have bumped to C++17? Or perhaps there are other reasons for the selection?

RAJA/include/RAJA/internal/MemUtils_CPU.hpp

Line 46 in 05256aa

#if defined(RAJA_HAVE_POSIX_MEMALIGN)

[rhornung67]

@MrBurmark @artv3 will you please comment on @smithsg84 question above about removing the RAJA wrapper and going with C++ std library directly?

[rhornung67]

Thanks @smithsg84 As you can see we've accumulated vestigial code over the years as we've evolved through C++ standard versions.

[adayton1]

I would be inclined to use std::aligned_alloc and drop the others.

[MrBurmark]

I don't know of a performance reason to prefer one aligned allocation function over another. I'm in favor of using the std version.