Make internal/private GVs implicitly dso_local.

While updating clang tests for having clang set dso_local I noticed
that:

- There are *a lot* of tests to update.
- Many of the updates are redundant.

They are redundant because a GV is "obviously dso_local". This patch
starts formalizing that a bit by requiring that internal and private
GVs be dso_local too. Since they all are, we don't have to print
dso_local to the textual representation, making it a bit more compact
and easier to read.

llvm-svn: 322317
diff --git a/llvm/test/ThinLTO/X86/alias_import.ll b/llvm/test/ThinLTO/X86/alias_import.ll
index ee4d533..da4d52a 100644
--- a/llvm/test/ThinLTO/X86/alias_import.ll
+++ b/llvm/test/ThinLTO/X86/alias_import.ll
@@ -57,11 +57,11 @@
 ; IMPORT-DAG: declare void @globalfuncLinkonceAlias()
 ; IMPORT-DAG: define available_externally void @globalfuncWeakODRAlias()
 ; IMPORT-DAG: define available_externally void @globalfuncLinkonceODRAlias()
-; IMPORT-DAG: define available_externally void @internalfuncAlias()
+; IMPORT-DAG: define available_externally dso_local void @internalfuncAlias()
 ; IMPORT-DAG: declare void @internalfuncWeakAlias()
 ; IMPORT-DAG: declare void @internalfuncLinkonceAlias()
-; IMPORT-DAG: define available_externally void @internalfuncWeakODRAlias()
-; IMPORT-DAG: define available_externally void @internalfuncLinkonceODRAlias()
+; IMPORT-DAG: define available_externally dso_local void @internalfuncWeakODRAlias()
+; IMPORT-DAG: define available_externally dso_local void @internalfuncLinkonceODRAlias()
 ; IMPORT-DAG: define available_externally void @weakODRfuncAlias()
 ; IMPORT-DAG: declare void @weakODRfuncWeakAlias()
 ; IMPORT-DAG: declare void @weakODRfuncLinkonceAlias()