Implement builtins for cl_khr_global_int32_base_atomics extension

git-svn-id: https://llvm.org/svn/llvm-project/libclc/trunk@195021 91177308-0d34-0410-b5e6-96231b3b80d8
Implement round builtin

git-svn-id: https://llvm.org/svn/llvm-project/libclc/trunk@195022 91177308-0d34-0410-b5e6-96231b3b80d8
R600: Add aliases for Sea Islands GPUs

git-svn-id: https://llvm.org/svn/llvm-project/libclc/trunk@195023 91177308-0d34-0410-b5e6-96231b3b80d8