Debug Info: Fix for break due to r181271

Apparently we didn't keep an association of Compile Unit metadata nodes
to DIEs so looking up that parental context failed & thus caused no
DW_TAG_imported_modules to be emitted at the CU scope. Fix this by
adding the mapping & sure up the test case to verify this.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181339 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/DebugInfo/namespace.ll b/test/DebugInfo/namespace.ll
index a7dcf7c..3d2a611 100644
--- a/test/DebugInfo/namespace.ll
+++ b/test/DebugInfo/namespace.ll
@@ -23,6 +23,8 @@
 ; CHECK-NEXT: DW_AT_decl_file{{.*}}(0x0[[F1]])
 ; CHECK-NEXT: DW_AT_decl_line{{.*}}(0x04)
 ; CHECK-NEXT: DW_AT_import{{.*}}=> {[[NS2]]})
+; CHECK: NULL
+; CHECK-NOT: NULL
 
 ; CHECK: DW_TAG_subprogram
 ; CHECK-NEXT: DW_AT_MIPS_linkage_name
@@ -39,6 +41,15 @@
 ; CHECK-NEXT: DW_AT_decl_file{{.*}}(0x0[[F2]])
 ; CHECK-NEXT: DW_AT_decl_line{{.*}}(0x0b)
 ; CHECK-NEXT: DW_AT_import{{.*}}=> {[[NS2]]})
+; CHECK: NULL
+; CHECK: NULL
+; CHECK-NOT: NULL
+
+; CHECK: DW_TAG_imported_module
+; Same bug as above, this should be F2, not F1
+; CHECK-NEXT: DW_AT_decl_file{{.*}}(0x0[[F1]])
+; CHECK-NEXT: DW_AT_decl_line{{.*}}(0x07)
+; CHECK-NEXT: DW_AT_import{{.*}}=> {[[NS1]]})
 
 ; CHECK: file_names[  [[F1]]]{{.*}}debug-info-namespace.cpp
 ; CHECK: file_names[  [[F2]]]{{.*}}foo.cpp