Cannot find system headers on macos Sonoma 14.4.1 and llvm 17

[renehiemstra]

I get an error that the system headers are not found when including them using terralib.includec(...), e.g.

    local io = terralib.includec("stdio.h")

[renehiemstra]

llvm behavior seems to have changed. "sysroot" no longer needs to be set to match clang behavior in terralib.lua, line 3520. Lines 3518-3522 can be commented out to make it work in llvm 17.