[PATCH] Document new LLVM CMake interface and emit warning when using llvm_map_components_to_libraries

[Dan Liew]

Okay merged in

r214077
r214078

and into LLVM release 3_5 in r214079 and r214080.

I've updated the LLVM3.5 release notes in r214083

> Users likely already refer to the current document for the old CMake
> usage instructions.  That location should be updated as your patch
> does now.  If another document could benefit from similar information
> then you could add it there too or link them.

Okay fair point. I'll add a small link in Projects.rst to the documentation
I just committed.

>> An alternative I guess would be to fix up LLD and Clang so that they
>> use the new LLVM Exported targets when built outside the LLVM build
>> tree (currently they invoke the llvm-config executable to get the
>> information they need) and once that works properly document this
>> process in Projects.rst. If you think that's sensible then a
>> discussion about this should probably go to llvm-dev.
>
> Yes, that is sensible.  That is why I added those LLVM_BUILD_* values
> to the LLVMConfig in the build tree in the first place.

Okay when I find some free time I'll take a look at how this might be
done and based on my finding I'll e-mail llvm-dev.

Thanks a lot for your help reviewing my CMake patches. At least all
these features are now going to be in the LLVM 3.5 release :)

Thanks,
Dan.