native linking export files, including running sed to prepend underscores
on darwin, and make use of it in libLTO and libEnhancedDisassembly.
Remove the leading underscores from library export files so that they
work with the new EXPORTED_SYMBOL_FILE support.
llvm-svn: 101399
Add lto_codegen_set_assembler_path() API which allows the linker to specify the
path to the assembler tool to run. When assembler is used (instead of compiler)
different command line options are used.
Add LTO_API_VERSION #define so clients (linkers) can conditionalize use of new APIs.
llvm-svn: 72823
