[CMake] add_llvm_symbol_exports: Use ${native_export_file} instead of equivalent constant "symbol.*', since it is defined.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198163 91177308-0d34-0410-b5e6-96231b3b80d8
[CMake] add_llvm_symbol_exports: Use unique name for each target.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198164 91177308-0d34-0410-b5e6-96231b3b80d8
[CMake] Fix add_llvm_loadble_module.

Thanks to Edward-san, to let me know.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198165 91177308-0d34-0410-b5e6-96231b3b80d8
Fix mis-merging in AddLLVM.cmake. Sorry.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198166 91177308-0d34-0410-b5e6-96231b3b80d8