Monotone: use Boost 1.49

Closes #19851.
ninja: add URL for HEAD version

Closes #20928.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
CLT is just CLT now; not "for Xcode".

References #17383.
libewf - fix download link

Closes #20913.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
denominator 2.1.0

Closes #20946.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>