ELF: Include archive names in error messages.

If object files are drawn from archive files, the error message should
be something like "conflict symbols in foo.a(bar.o) and baz.o" instead
of "conflict symbols in bar.o and baz.o". This patch implements that.

llvm-svn: 259475
diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp
index fe0a3f5..4fbf202 100644
--- a/lld/ELF/Driver.cpp
+++ b/lld/ELF/Driver.cpp
@@ -95,8 +95,9 @@
     return;
   case file_magic::archive:
     if (WholeArchive) {
+      StringRef S = MBRef.getBufferIdentifier();
       for (MemoryBufferRef MB : getArchiveMembers(MBRef))
-        Files.push_back(createObjectFile(MB));
+        Files.push_back(createObjectFile(MB, S));
       return;
     }
     Files.push_back(make_unique<ArchiveFile>(MBRef));