CodeGen: mark ObjC cstring literals as unnamed_addr

These are all emitted into a section with a cstring_literal attribute.  The
attribute permits the linker to coalesce the string contents.  The address of
the strings are not important.

llvm-svn: 281855
diff --git a/clang/test/CodeGenObjC/nsvalue-objc-boxable-mac.m b/clang/test/CodeGenObjC/nsvalue-objc-boxable-mac.m
index 0f7c37d..749dc0e 100644
--- a/clang/test/CodeGenObjC/nsvalue-objc-boxable-mac.m
+++ b/clang/test/CodeGenObjC/nsvalue-objc-boxable-mac.m
@@ -5,7 +5,7 @@
 // CHECK:      [[CLASS:@.*]]        = external global %struct._class_t
 // CHECK:      [[NSVALUE:@.*]]      = {{.*}}[[CLASS]]{{.*}}
 // CHECK:      [[RANGE_STR:.*]]     = {{.*}}_NSRange=QQ{{.*}}
-// CHECK:      [[METH:@.*]]         = private constant {{.*}}valueWithBytes:objCType:{{.*}}
+// CHECK:      [[METH:@.*]]         = private unnamed_addr constant {{.*}}valueWithBytes:objCType:{{.*}}
 // CHECK:      [[VALUE_SEL:@.*]]    = {{.*}}[[METH]]{{.*}}
 // CHECK:      [[POINT_STR:.*]]     = {{.*}}_NSPoint=dd{{.*}}
 // CHECK:      [[SIZE_STR:.*]]      = {{.*}}_NSSize=dd{{.*}}