We should be using bin/clang, not the build/lightining/bin/clang since
build/ is the project's internal build directory. This patch corrects
this where possible.
However, lightning does not install all it's end user files under out/
so some headers can not be found anywhere in out/ in an incremental build.
This header (opencl-c.h) if fetched out of the lightning source tree if
necessary.
Change-Id: I083d8b27bb39dd615fba3bb0711a789318f95e77
Sean Keely
f62017f4a5