[Driver][SYCL][NFC] Improve testing of -fsycl-device-only (#2708)

Add a few key checks for -fsycl-device-only which were previously
missing when comparing to -fsycl device compilations.

Author: mdtoguchi

clang/test/Driver/sycl.c

@@ -36,8 +36,10 @@
 // RUN: %clang -### -fsycl-device-only -c -emit-llvm %s 2>&1 | FileCheck %s --check-prefix=COMBINED
 // RUN: %clangxx -### -fsycl-device-only %s 2>&1 | FileCheck %s --check-prefix=DEFAULT
 // RUN: %clang_cl -### -fsycl-device-only %s 2>&1 | FileCheck %s --check-prefix=DEFAULT
+// RUN: %clangxx -### -fsycl-device-only -fsycl-unnamed-lambda %s 2>&1 | FileCheck %s --check-prefix=CHECK-LAMBDA
+// RUN: %clang_cl -### -fsycl-device-only -fsycl-unnamed-lambda %s 2>&1 | FileCheck %s --check-prefix=CHECK-LAMBDA
 
-// DEFAULT: "-triple" "spir64-unknown-{{.*}}-sycldevice{{.*}}" "-fsycl-is-device"{{.*}} "-emit-llvm-bc"
+// DEFAULT: "-triple" "spir64-unknown-{{.*}}-sycldevice{{.*}}" "-fsycl-is-device"{{.*}} "-sycl-std=2020"{{.*}} "-emit-llvm-bc"
 // DEFAULT: "-internal-isystem" "{{.*}}bin{{[/\\]+}}..{{[/\\]+}}include{{[/\\]+}}sycl"
 // DEFAULT: "-internal-isystem" "{{.*lib.*clang.*include}}"
 // DEFAULT: "-std=c++17"
@@ -49,6 +51,7 @@
 // TARGET: "-triple" "spir64-unknown-linux-sycldevice"{{.*}} "-fsycl-is-device"{{.*}} "-emit-llvm-bc"
 // COMBINED: "-triple" "spir64-unknown-{{.*}}-sycldevice"{{.*}} "-fsycl-is-device"{{.*}} "-emit-llvm-bc"
 // TEXTUAL: "-triple" "spir64-unknown-{{.*}}-sycldevice{{.*}}" "-fsycl-is-device"{{.*}} "-emit-llvm"
+// CHECK-LAMBDA: "-fsycl-unnamed-lambda"
 
 /// -fsycl-device-only triple checks
 // RUN: %clang -fsycl-device-only -target x86_64-unknown-linux-gnu -### %s 2>&1 \