<sys/resource.h> is available. This should fix out-of-tree builds, at the cost
of not providing the higher rlimits to stage 1 clang when built with an old
host compiler not implementing this feature yet (bootstrap builds should be
fine, though).


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@279112 91177308-0d34-0410-b5e6-96231b3b80d8