Set LLVM_EXPORTED_SYMBOL_FILE in CMakeLists whose corresponding Makefiles do so.

(unittests/ExecutionEngine/JIT/CMakeLists.txt is still missing for now, since
it handles export files in a strange way: It generates a .exports file from a
.def file instead of the other way round.)


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198183 91177308-0d34-0410-b5e6-96231b3b80d8