[cfi] Use __builtin version of __clear_cache.
[cfi] Use __builtin version of __clear_cache.

__builtin___clear_cache is also present on X86 and does the right thing (i.e. nop) there.

git-svn-id: c199f293c43da69278bea8e88f92242bf3aa95f7@335997 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt