Fix identify_magic() with mach-o stub dylibs.

The wrong value was returned and the unittest did not cover the stub dylib case.

llvm-svn: 217933
diff --git a/llvm/lib/Support/Path.cpp b/llvm/lib/Support/Path.cpp
index 781c17c..7e02f5f 100644
--- a/llvm/lib/Support/Path.cpp
+++ b/llvm/lib/Support/Path.cpp
@@ -999,7 +999,7 @@
         case 6: return file_magic::macho_dynamically_linked_shared_lib;
         case 7: return file_magic::macho_dynamic_linker;
         case 8: return file_magic::macho_bundle;
-        case 9: return file_magic::macho_dynamic_linker;
+        case 9: return file_magic::macho_dynamically_linked_shared_lib_stub;
         case 10: return file_magic::macho_dsym_companion;
       }
       break;