[llvm] Update MachOObjectFile::exports interface

This diff removes the second argument of the method MachOObjectFile::exports.
In all in-tree uses this argument is equal to "this" and 
without this argument the interface seems to be cleaner.

Test plan: make check-all

llvm-svn: 309462
diff --git a/llvm/lib/Object/MachOObjectFile.cpp b/llvm/lib/Object/MachOObjectFile.cpp
index 579faf6..af8ee40 100644
--- a/llvm/lib/Object/MachOObjectFile.cpp
+++ b/llvm/lib/Object/MachOObjectFile.cpp
@@ -2908,9 +2908,8 @@
   return make_range(export_iterator(Start), export_iterator(Finish));
 }
 
-iterator_range<export_iterator> MachOObjectFile::exports(Error &Err,
-                                  const MachOObjectFile *O) const {
-  return exports(Err, getDyldInfoExportsTrie(), O);
+iterator_range<export_iterator> MachOObjectFile::exports(Error &Err) const {
+  return exports(Err, getDyldInfoExportsTrie(), this);
 }
 
 MachORebaseEntry::MachORebaseEntry(Error *E, const MachOObjectFile *O,