libcxx: fix merge_archives error variable name

Differential Revision: https://reviews.llvm.org/D37728

llvm-svn: 313084
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: f922501d98153df01ee12a0b8b7b12ecdef5bfe7
diff --git a/utils/merge_archives.py b/utils/merge_archives.py
index db101da..ee0f7d3 100755
--- a/utils/merge_archives.py
+++ b/utils/merge_archives.py
@@ -120,7 +120,7 @@
 
     files = glob.glob(os.path.join(temp_directory_root, '*.o*'))
     if not files:
-        print_and_exit('Failed to glob for %s' % glob_path)
+        print_and_exit('Failed to glob for %s' % temp_directory_root)
     cmd = [ar_exe, '-qc', args.output] + files
     execute_command_verbose(cmd, cwd=temp_directory_root, verbose=args.verbose)