[SYCL] Use auto & in loop to avoid unnecessary copies (#15098)

Switched from `auto` to `auto &` in the loop to prevent copying of
`TemplateArgument` objects, optimizing performance in
clang::​SYCLIntegrationHeader::​emit(llvm::​raw_ostream &).

Author: smanna12

clang/lib/Sema/SemaSYCL.cpp

@@ -6326,7 +6326,7 @@ void SYCLIntegrationHeader::emit(raw_ostream &O) {
       ArrayRef<TemplateArgument> A = TAL->asArray();
       bool FirstParam = true;
       O << "<";
-      for (auto X : A) {
+      for (const auto &X : A) {
         if (FirstParam)
           FirstParam = false;
         else