clang uses the llvm backend, so define __llvm__ like llvm-gcc.   Additionally, define __clang__ so clients can predicate based on clang features.
clang uses the llvm backend, so define __llvm__ like llvm-gcc.  
Additionally, define __clang__ so clients can predicate based on
clang features.


git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@52788 91177308-0d34-0410-b5e6-96231b3b80d8

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