[COFF] Remove a duplicate import_directory_table_entry definition

We had import_directory_table_entry and
coff_import_directory_table_entry, remove one.  Also, factor out the
logic which determins if a descriptor is a terminator.

llvm-svn: 277296
diff --git a/llvm/tools/llvm-objdump/COFFDump.cpp b/llvm/tools/llvm-objdump/COFFDump.cpp
index 3ec6a1f..b7ab860 100644
--- a/llvm/tools/llvm-objdump/COFFDump.cpp
+++ b/llvm/tools/llvm-objdump/COFFDump.cpp
@@ -353,7 +353,7 @@
     return;
   outs() << "The Import Tables:\n";
   for (const ImportDirectoryEntryRef &DirRef : Obj->import_directories()) {
-    const import_directory_table_entry *Dir;
+    const coff_import_directory_table_entry *Dir;
     StringRef Name;
     if (DirRef.getImportTableEntry(Dir)) return;
     if (DirRef.getName(Name)) return;