(Only the first 10 of 15 ports in this commit are shown above. )
Upgrade the llvm development ports to r193887. We're about two weeks
from the LLVM 3.4 branch starting.
Apply the clang portion of r255321 from base switching the default C++
library to libc++ on 10+.
Correct clang's notion of the underlying type of (u)intmax_t on MIPS64.