Reapply r183721, reverted in r183776, with a fix for a bug in the former (we
were lacking ExprWithCleanups nodes in some cases where the new approach to
lifetime extension needed them).

Original commit message:

Rework IR emission for lifetime-extended temporaries. Instead of trying to walk
into the expression and dig out a single lifetime-extended entity and manually
pull its cleanup outside the expression, instead keep a list of the cleanups
which we'll need to emit when we get to the end of the full-expression. Also
emit those cleanups early, as EH-only cleanups, to cover the case that the
full-expression does not terminate normally. This allows IR generation to
properly model temporary lifetime when multiple temporaries are extended by the
same declaration.

We have a pre-existing bug where an exception thrown from a temporary's
destructor does not clean up lifetime-extended temporaries created in the same
expression and extended to automatic storage duration; that is not fixed by
this patch.

llvm-svn: 183859
diff --git a/clang/test/CodeGenCXX/cxx11-thread-local.cpp b/clang/test/CodeGenCXX/cxx11-thread-local.cpp
index 2987703..04ca089 100644
--- a/clang/test/CodeGenCXX/cxx11-thread-local.cpp
+++ b/clang/test/CodeGenCXX/cxx11-thread-local.cpp
@@ -35,7 +35,7 @@
 
 // CHECK: @_ZZ8tls_dtorvE1u = internal thread_local global
 // CHECK: @_ZGVZ8tls_dtorvE1u = internal thread_local global i8 0
-// CHECK: @_ZGRZ8tls_dtorvE1u = internal thread_local global
+// CHECK: @_ZGRZ8tls_dtorvE1u = private thread_local global
 
 // CHECK: @_ZGVN1VIiE1mE = weak_odr thread_local global i64 0