Log Message:
libcxx: updated to 8.0.0:

What’s New in Libc++ 8.0.0?

API Changes

Building libc++ for Mac OSX 10.6 is not supported anymore.
Starting with LLVM 8.0.0, users that wish to link together translation units \ 
built with different versions of libc++’s headers into the same final linked \ 
image MUST define the _LIBCPP_HIDE_FROM_ABI_PER_TU macro to 1 when building \ 
those translation units. Not defining _LIBCPP_HIDE_FROM_ABI_PER_TU to 1 and \ 
linking translation units built with different versions of libc++’s headers \ 
together may lead to ODR violations and ABI issues. On the flipside, code size \ 
improvements should be expected for everyone not defining the macro.
Starting with LLVM 8.0.0, std::dynarray has been removed from the library. \ 
std::dynarray was a feature proposed for C++14 that was pulled from the Standard \ 
at the last minute and was never standardized. Since there are no plans to \ 
standardize this facility it is being removed.
Starting with LLVM 8.0.0, std::bad_array_length has been removed from the \ 
library. std::bad_array_length was a feature proposed for C++14 alongside \ 
std::dynarray, but it never actually made it into the C++ Standard. There are no \ 
plans to standardize this feature at this time. Formally speaking, this removal \ 
constitutes an ABI break because the symbols were shipped in the shared library. \ 
However, on macOS systems, the feature was not usable because it was hidden \ 
behind availability annotations. We do not expect any actual breakage to happen \ 
from this change.