Revert "Revert "PR14606: debug info imported_module support""

This reverts commit r179840 with a fix to test/DebugInfo/two-cus-from-same-file.ll

I'm not sure why that test only failed on ARM & MIPS and not X86 Linux, even
though the debug info was clearly invalid on all of them, but this ought to fix
it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179996 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/DebugInfo/2010-04-19-FramePtr.ll b/test/DebugInfo/2010-04-19-FramePtr.ll
index f9e90cd..88eebe6 100644
--- a/test/DebugInfo/2010-04-19-FramePtr.ll
+++ b/test/DebugInfo/2010-04-19-FramePtr.ll
@@ -25,7 +25,7 @@
 !0 = metadata !{i32 2, i32 0, metadata !1, null}
 !1 = metadata !{i32 786478, metadata !2, metadata !"foo", metadata !"foo", metadata !"foo", metadata !2, i32 2, metadata !4, i1 false, i1 true, i32 0, i32 0, null, i1 false, i32 ()* @foo, null, null, null, i32 2} ; [ DW_TAG_subprogram ]
 !2 = metadata !{i32 786473, metadata !"a.c", metadata !"/tmp", metadata !3} ; [ DW_TAG_file_type ]
-!3 = metadata !{i32 786449, i32 1, metadata !2, metadata !"4.2.1 (Based on Apple Inc. build 5658) (LLVM build)", i1 false, metadata !"", i32 0, null, null, metadata !9, null, metadata !""} ; [ DW_TAG_compile_unit ]
+!3 = metadata !{i32 786449, i32 1, metadata !2, metadata !"4.2.1 (Based on Apple Inc. build 5658) (LLVM build)", i1 false, metadata !"", i32 0, null, null, metadata !9, null,  null, metadata !""} ; [ DW_TAG_compile_unit ]
 !4 = metadata !{i32 786453, metadata !2, metadata !"", metadata !2, i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !5, i32 0, null} ; [ DW_TAG_subroutine_type ]
 !5 = metadata !{metadata !6}
 !6 = metadata !{i32 786468, metadata !2, metadata !"int", metadata !2, i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ]