Merge topic 'cmuvprocesschain-external-stream-fd'

b65d54e876 cmUVStreambuf: Update URL for example code
0878306386 cmUVStream: Add cmUVStreamRead() function
b8fd273ed7 cmUVProcessChain: Return output and error streams as file descriptors
ec81d40be4 cmUVPipeIStream: Add cmUVPipeIStream
3b6c5efc08 cm::append: Add support for std::basic_string on SPARC/SunPro

Acked-by: Kitware Robot <kwrobot@kitware.com>
Tested-by: buildbot <buildbot@kitware.com>
Merge-request: !8559