DebugInfo: Remove some unneeded conditionals now that DIBuilder no longer emits zero-length arrays as {i32 0}

A bunch of test cases needed to be cleaned up for this, many my fault -
when implementid imported modules I updated test cases by simply
duplicating the prior metadata field - which wasn't always the empty
metadata entry.

llvm-svn: 200731
diff --git a/llvm/test/DebugInfo/X86/stmt-list-multiple-compile-units.ll b/llvm/test/DebugInfo/X86/stmt-list-multiple-compile-units.ll
index 4e14e60..71cddbd 100644
--- a/llvm/test/DebugInfo/X86/stmt-list-multiple-compile-units.ll
+++ b/llvm/test/DebugInfo/X86/stmt-list-multiple-compile-units.ll
@@ -74,7 +74,7 @@
 !llvm.dbg.cu = !{!0, !10}
 !llvm.module.flags = !{!25}
 !0 = metadata !{i32 786449, metadata !23, i32 12, metadata !"clang version 3.3", i1 false, metadata !"", i32 0, metadata !1, metadata !1, metadata !3, metadata !1,  metadata !1, metadata !""} ; [ DW_TAG_compile_unit ]
-!1 = metadata !{i32 0}
+!1 = metadata !{}
 !3 = metadata !{metadata !5}
 !5 = metadata !{i32 786478, metadata !23, metadata !6, metadata !"test", metadata !"test", metadata !"", i32 2, metadata !7, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 false, i32 (i32)* @test, null, null, metadata !1, i32 3} ; [ DW_TAG_subprogram ] [line 2] [def] [scope 3] [test]
 !6 = metadata !{i32 786473, metadata !23} ; [ DW_TAG_file_type ]