[CodeGenModule] Assume dso_local for -fpic -fno-semantic-interposition

Summary:
Clang -fpic defaults to -fno-semantic-interposition (GCC -fpic defaults
to -fsemantic-interposition).
Users need to specify -fsemantic-interposition to get semantic
interposition behavior.

Semantic interposition is currently a best-effort feature. There may
still be some cases where it is not handled well.

Reviewers: peter.smith, rnk, serge-sans-paille, sfertile, jfb, jdoerfert

Subscribers: dschuff, jyknight, dylanmckay, nemanjai, jvesely, kbarton, fedor.sergeev, asb, rbar, johnrusso, simoncook, sabuasal, niosHD, jrtc27, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, arphaman, PkmX, jocewei, jsji, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, luismarques, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D73865
diff --git a/clang/test/CodeGen/catch-nullptr-and-nonzero-offset-when-nullptr-is-defined.c b/clang/test/CodeGen/catch-nullptr-and-nonzero-offset-when-nullptr-is-defined.c
index 3f1e225..f8db72f 100644
--- a/clang/test/CodeGen/catch-nullptr-and-nonzero-offset-when-nullptr-is-defined.c
+++ b/clang/test/CodeGen/catch-nullptr-and-nonzero-offset-when-nullptr-is-defined.c
@@ -25,7 +25,7 @@
 #endif
 
 char *add_unsigned(char *base, unsigned long offset) {
-  // CHECK:                           define i8* @add_unsigned(i8* %[[BASE:.*]], i64 %[[OFFSET:.*]])
+  // CHECK:                           define dso_local i8* @add_unsigned(i8* %[[BASE:.*]], i64 %[[OFFSET:.*]])
   // CHECK-NEXT:                      [[ENTRY:.*]]:
   // CHECK-NEXT:                        %[[BASE_ADDR:.*]] = alloca i8*, align 8
   // CHECK-NEXT:                        %[[OFFSET_ADDR:.*]] = alloca i64, align 8