Update to 1.8.7:

NEW IN WAF 1.8.7
----------------
* Fixed the default libdir installation suffix on Redhat 64-bit systems #1536
* Fixed the Python 2.6 detection on Redhat systems #1538
* Enabled gccdeps to work with clang
* Fixed the detection of clang from the gcc tools
* Added orig_run_str to help subclasses (do not use Task.hcode)
* Fixed the detection of older clang compilers versions
* NEC compiler support
* Enabled batched_cc.py to work with msvc too
* Enabled unity.py to process c files
* Faster dependency calculation in c_dumbpreproc
* New stracedeps example (cfg blog entry)
* Added support for xz compression in waf and waf dist (Python 3.5)

(wiz)