devel/libcwd: update to 1.0.6

[cpm]

Summary

devel/libcwd: update to 1.0.6

- Add LICENSE section
- Switch to GCC=yes since this version adds support for GCC 5.x and 6.x
- Remove unrecognized configuration option: --disable-pch
- Bump library version in pkg-plist
- Take maintainership

Changes:
  Support for g++ 6.x, 5.x and DWARF version 4.

  Added channel_ct::operator(bool)
  This allows one to turn off debug output for a channel that is on
  on a per invocation basis by doing:
    
	  Dout(dc::notice(cond), ...);
    
  which then will only print debug output if 'cond' is true (and
  dc::notice is on).

  Added libcwd/cwlist.h to libcwd - this isn't used by
  libcwd itself, it's just an extra gadget for you.

  Bug fixes:

  Reallocating a memory block that was originally allocated
  in a different thread could lead to undefined behavior (when
  memory allocation checking is on, which is the default).

[gerald]

Do you need / are you seeking approval for this?

If so, this looks good to me (and thanks for doing this update / improvement)!