Add a missing error handling to llvm-lto.

llvm-svn: 257395
diff --git a/llvm/test/tools/llvm-lto/error.ll b/llvm/test/tools/llvm-lto/error.ll
new file mode 100644
index 0000000..8f11270
--- /dev/null
+++ b/llvm/test/tools/llvm-lto/error.ll
@@ -0,0 +1,2 @@
+; RUN: not llvm-lto foobar 2>&1 | FileCheck %s
+; CHECK: llvm-lto: error loading file 'foobar': No such file or directory