LLVM low level support for a standard C++ library

 libc++abi is another implementation of low level support for a standard C++
 library.
 .
 Features and Goals
 .
   * Correctness as defined by the C++ standards.
   * Provide a portable sublayer to ease the porting of libc++
 .
 This is a dependency package providing low level support to
 LLVM C++ Standard library.