Add support for archives with no symbol table or string table.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185664 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Object/Archive.cpp b/lib/Object/Archive.cpp
index 8206b0a..0b819f4 100644
--- a/lib/Object/Archive.cpp
+++ b/lib/Object/Archive.cpp
@@ -104,7 +104,7 @@
   : Binary(Binary::ID_Archive, source) {
   // Check for sufficient magic.
   if (!source || source->getBufferSize()
-                 < (8 + sizeof(ArchiveMemberHeader) + 2) // Smallest archive.
+                 < (8 + sizeof(ArchiveMemberHeader)) // Smallest archive.
               || StringRef(source->getBufferStart(), 8) != Magic) {
     ec = object_error::invalid_file_type;
     return;