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/ARM/debug-info-blocks.ll b/test/CodeGen/ARM/debug-info-blocks.ll
index 0fbd63e..96eeb43 100644
--- a/test/CodeGen/ARM/debug-info-blocks.ll
+++ b/test/CodeGen/ARM/debug-info-blocks.ll
@@ -96,7 +96,7 @@
 !147 = metadata !{metadata !1, metadata !1, metadata !5, metadata !5, metadata !9, metadata !14, metadata !19, metadata !19, metadata !14, metadata !14, metadata !14, metadata !19, metadata !19, metadata !19}
 !148 = metadata !{metadata !23}
 
-!0 = metadata !{i32 786449, i32 0, i32 16, metadata !"MyLibrary.i", metadata !"/Volumes/Sandbox/llvm", metadata !"Apple clang version 2.1", i1 false, metadata !"", i32 2, metadata !147, null, metadata !148, null, metadata !""} ; [ DW_TAG_compile_unit ]
+!0 = metadata !{i32 786449, i32 0, i32 16, metadata !40, metadata !"Apple clang version 2.1", i1 false, metadata !"", i32 2, metadata !147, null, metadata !148, null, metadata !""} ; [ DW_TAG_compile_unit ]
 !1 = metadata !{i32 786433, metadata !0, metadata !"", metadata !2, i32 248, i64 32, i64 32, i32 0, i32 0, i32 0, metadata !3, i32 0, i32 0} ; [ DW_TAG_enumeration_type ]
 !2 = metadata !{i32 786473, metadata !"header.h", metadata !"/Volumes/Sandbox/llvm", metadata !0} ; [ DW_TAG_file_type ]
 !3 = metadata !{metadata !4}