Attempt to recover gdb bot after r174445.

Failure: undefined symbol 'Lline_table_start0'.
Root-cause: we use a symbol subtraction to calculate at_stmt_list, but
the line table entries are not dumped in the assembly.
Fix: use zero instead of a symbol subtraction for Compile Unit 0.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174479 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/DebugInfo/X86/stringpool.ll b/test/DebugInfo/X86/stringpool.ll
index 4e2a2a2..1e08d54 100644
--- a/test/DebugInfo/X86/stringpool.ll
+++ b/test/DebugInfo/X86/stringpool.ll
@@ -23,8 +23,8 @@
 ; LINUX-NEXT: .quad   yyyy
 
 ; Verify that we refer to 'yyyy' without a relocation.
-; DARWIN: Lset6 = Linfo_string3-Linfo_string          ## DW_AT_name
-; DARWIN-NEXT:        .long   Lset6
+; DARWIN: Lset5 = Linfo_string3-Linfo_string          ## DW_AT_name
+; DARWIN-NEXT:        .long   Lset5
 ; DARWIN-NEXT:        .long   39                      ## DW_AT_type
 ; DARWIN-NEXT:        .byte   1                       ## DW_AT_external
 ; DARWIN-NEXT:        .byte   1                       ## DW_AT_decl_file