[LLD][ELF] - Add a test case.

This covers the following line with a test:
https://github.com/llvm-mirror/lld/blob/master/ELF/InputFiles.cpp#L487

llvm-svn: 339876

lld/test/ELF/invalid/linkorder-invalid-sec.test

@@ -0,0 +1,16 @@
+# REQUIRES: x86
+# RUN: yaml2obj %s -o %t.o
+# RUN: not ld.lld %t.o -o %t.exe 2>&1 | FileCheck %s
+# CHECK: invalid sh_link index: 12345
+
+--- !ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_REL
+  Machine:         EM_X86_64
+Sections:
+  - Name:          .linkorder
+    Type:          SHT_PROGBITS
+    Flags:         [ SHF_ALLOC, SHF_EXECINSTR, SHF_LINK_ORDER ]
+    Link:          12345