Upcoming changes libc++abi's CMake target names.

Hi All,

If you depend on the CMake target name 'cxxabi' please read this email.

In order to better support linking libc++ I am introducing a change to
make libc++abi build as both a static and shared library
simultaneously. This behavior will be enabled by default. To turn of
building either library you can use the following CMake options:


At least one of these options must be enabled. The CMake target names
for the static/shared libraries are now:

- cxxabi_static
- cxxabi_shared

However the important change is that the CMake target name `cxxabi` is
being replaced with a meta-target that builds both cxxabi_static and
cxxabi_shared. You can no longer use this target to link your library
to libc++abi.

Please let me know if you think this will cause any problems.


The changes have been introduced as r231075 and r231076. Please
update both your working copies of both libc++ and libc++abi.