Delete unnecessary generality in loadFile.

loadFile could load mulitple files just because yaml has a feature for
putting multiple documents in one file.

Designing a linker around what yaml can do seems like a bad idea to
me. This patch changes it to read a single file.

There are further improvements to be done to the api and they
will follow shortly.

llvm-svn: 235724
diff --git a/lld/lib/ReaderWriter/MachO/MachOLinkingContext.cpp b/lld/lib/ReaderWriter/MachO/MachOLinkingContext.cpp
index 9b5837c..aff6c87 100644
--- a/lld/lib/ReaderWriter/MachO/MachOLinkingContext.cpp
+++ b/lld/lib/ReaderWriter/MachO/MachOLinkingContext.cpp
@@ -623,9 +623,11 @@
   if (mbOrErr.getError())
     return nullptr;
 
-  std::vector<std::unique_ptr<File>> files;
-  if (registry().loadFile(std::move(mbOrErr.get()), files))
+  std::unique_ptr<File> file;
+  if (registry().loadFile(std::move(mbOrErr.get()), file))
     return nullptr;
+  std::vector<std::unique_ptr<File>> files;
+  files.push_back(std::move(file));
   assert(files.size() == 1 && "expected one file in dylib");
   files[0]->parse();
   MachODylibFile* result = reinterpret_cast<MachODylibFile*>(files[0].get());