Which branch are you building, release or master?
The two lines about libmono-corlib4.0-cil and mono-gcms look familiar, I wouldn’t worry about them. I believe they’re obsolete nowadays and no longer needed. What confuses me is that you’re using Ubuntu 16.04 but it’s telling you your Clang version is 3.5.2. My Ubuntu 16.04 installation has Clang 3.8 and I’m 99% sure I didn’t install it manually.
If you run ‘clang --version’, what do you get? If it’s 3.5.2, try installing 3.8 by following these instructions. If it’s 3.8 (IMO more likely), then I think the build script is failing to recognize your Clang and/or Ubuntu version. Try a fresh checkout of master, they added a few Clang 3.8 related changes two days ago.