clang-aarch64-linux-build-cache & clang-armv7-linux-build-cache are failing due to libcxxabi compile issues

Seems that they have been failing for a week due to libcxxabi compile issues.

http://lab.llvm.org:8011/#/builders/103
http://lab.llvm.org:8011/#/builders/35

Including Leandro as who seems to maintain the workers - could you take a look
at this? This could help committers from receiving "Buildbot failure in LLVM
Buildbot on" spam.

I can reproduce the failure. It looks like a side-effect of https://reviews.llvm.org/D88301 [libc++] Clean up logic around aligned/sized allocation and deallocation

Empirically it looks like __builtin_operator_new(__args...); needs clang 7.0 or above to compile, at least on Arm and AArch64. The build-bot is using clang 5.01.

It looks like to fix this the compiler on the buildbot will need upgrading or we'll need to retire the buildbot. I have some tickets lodged with an infrastructure team but until they are resolved I suggest ignoring it.

Peter

/home/tcwg-buildslave/buildslave/clang-aarch64-linux-build-cache/llvm/libcxxabi/../libcxx/include/new:236:33: error: too many arguments to function call, expected 1, have 2
  return __builtin_operator_new(__args...);
         ~~~~~~~~~~~~~~~~~~~~~~ ^~~~~~
/home/tcwg-buildslave/buildslave/clang-aarch64-linux-build-cache/llvm/libcxxabi/../libcxx/include/new:257:12: note: in instantiation of function template specialization 'std::__1::__libcpp_operator_new<unsigned long, std::align_val_t>' requested here
    return __libcpp_operator_new(__size, __align_val);
           ^
/home/tcwg-buildslave/buildslave/clang-aarch64-linux-build-cache/llvm/libcxxabi/../libcxx/include/new:246:29: error: too many arguments to function call, expected 1, have 2
  __builtin_operator_delete(__args...);
  ~~~~~~~~~~~~~~~~~~~~~~~~~ ^~~~~~
/home/tcwg-buildslave/buildslave/clang-aarch64-linux-build-cache/llvm/libcxxabi/../libcxx/include/new:298:14: note: in instantiation of function template specialization 'std::__1::__libcpp_operator_delete<void *, std::align_val_t>' requested here
      return __libcpp_operator_delete(__ptr, __align_val);
             ^
2 errors generated.