[Clang] Fix use of deprecated method and missing triple

Fixes two buildbot errors caused by 4424c44 (#110102):

The first error, seen on some sanitizer bots:
https://lab.llvm.org/buildbot/#/builders/51/builds/9901

The initial commit used the deprecated getDeclaration intrinsic instead
of the non-deprecated getOrInsert- equivalent. This patch trivially
updates the code in question to use the new intrinsic.

The second error, seen on the clang-armv8-quick bot:
https://lab.llvm.org/buildbot/#/builders/154/builds/10983

One of the tests depends on a particular triple to get the exact output
expected by the test, but did not specify this triple; this patch adds
the triple in question.

Author: SLTozer

clang/lib/CodeGen/CGDecl.cpp

@@ -2587,9 +2587,10 @@ llvm::Function *CodeGenModule::getLLVMLifetimeEndFn() {
 
 /// Lazily declare the @llvm.fake.use intrinsic.
 llvm::Function *CodeGenModule::getLLVMFakeUseFn() {
-  if (!FakeUseFn)
-    FakeUseFn = llvm::Intrinsic::getDeclaration(&getModule(),
-                                                llvm::Intrinsic::fake_use);
+  if (FakeUseFn)
+    return FakeUseFn;
+  FakeUseFn = llvm::Intrinsic::getOrInsertDeclaration(
+      &getModule(), llvm::Intrinsic::fake_use);
   return FakeUseFn;
 }
 

clang/test/CodeGen/fake-use-sanitizer.cpp

@@ -1,5 +1,5 @@
-// RUN: %clang_cc1 %s -emit-llvm -fextend-variable-liveness -fsanitize=null -fsanitize-trap=null -o - | FileCheck --check-prefixes=CHECK,NULL --implicit-check-not=ubsantrap %s
-// RUN: %clang_cc1 %s -emit-llvm -fextend-variable-liveness -o - | FileCheck %s
+// RUN: %clang_cc1 %s -triple x86_64-unknown-linux-gnu -emit-llvm -fextend-variable-liveness -fsanitize=null -fsanitize-trap=null -o - | FileCheck --check-prefixes=CHECK,NULL --implicit-check-not=ubsantrap %s
+// RUN: %clang_cc1 %s -triple x86_64-unknown-linux-gnu -emit-llvm -fextend-variable-liveness -o - | FileCheck %s
 
 // With -fextend-lifetimes, the compiler previously generated a fake.use of any
 // reference variable at the end of the scope in which its alloca exists. This