Refactor filename/directory in DICompileUnit into a DIFile

This is the next step towards making the metadata for DIScopes have a common
prefix rather than having to delegate based on their tag type.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176913 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGen/PowerPC/dbg.ll b/test/CodeGen/PowerPC/dbg.ll
index d43d6a8..220e7ed 100644
--- a/test/CodeGen/PowerPC/dbg.ll
+++ b/test/CodeGen/PowerPC/dbg.ll
@@ -16,7 +16,7 @@
 
 !llvm.dbg.cu = !{!0}
 
-!0 = metadata !{i32 720913, i32 0, i32 12, metadata !"dbg.c", metadata !"/src", metadata !"clang version 3.1", i1 true, metadata !"", i32 0, metadata !1, metadata !1, metadata !3, metadata !1, metadata !""} ; [ DW_TAG_compile_unit ]
+!0 = metadata !{i32 720913, i32 0, i32 12, metadata !6, metadata !"clang version 3.1", i1 true, metadata !"", i32 0, metadata !1, metadata !1, metadata !3, metadata !1, metadata !""} ; [ DW_TAG_compile_unit ]
 !1 = metadata !{i32 0}
 !3 = metadata !{metadata !5}
 !5 = metadata !{i32 720942, i32 0, metadata !6, metadata !"main", metadata !"main", metadata !"", metadata !6, i32 1, metadata !7, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 true, i32 (i32, i8**)* @main, null, null, metadata !13} ; [ DW_TAG_subprogram ]