[SYCL] Some refactoring of integration header and fix one test

 Delete a dependence of sycl runtime
 Move include kernel_desc.hpp to higher than forward declarations.

Signed-off-by: Vladimir Lazarev <vladimir.lazarev@intel.com>

clang/lib/Sema/SemaSYCL.cpp

@@ -807,19 +807,20 @@ void SYCLIntegrationHeader::emitForwardClassDecls(
 
 void SYCLIntegrationHeader::emit(raw_ostream &O) {
   O << "// This is auto-generated SYCL integration header.\n";
+  O << "\n";
+
+  O << "#include <CL/sycl/detail/kernel_desc.hpp>\n";
+
   O << "\n";
   O << "// Forward declarations of templated kernel function types:\n";
 
   llvm::SmallPtrSet<const void *, 4> Printed;
-
   for (const KernelDesc &K : KernelDescs) {
     emitForwardClassDecls(O, K.NameType, Printed);
   }
   O << "\n";
 
-  O << "#include <CL/sycl/detail/kernel_desc.hpp>\n";
 
-  O << "\n";
 
   O << "namespace cl {\n";
   O << "namespace sycl {\n";

clang/test/CodeGenSYCL/integration_header.cpp

@@ -1,6 +1,8 @@
 // RUN: %clang --sycl -Xclang -fsycl-int-header=%t.h %s -c -o %T/kernel.spv
 // RUN: FileCheck -input-file=%t.h %s
 //
+// CHECK: #include <CL/sycl/detail/kernel_desc.hpp>
+//
 // CHECK: class first_kernel;
 // CHECK-NEXT: namespace second_namespace {
 // CHECK-NEXT: template <typename T> class second_kernel;
@@ -9,8 +11,6 @@
 // CHECK-NEXT: template <typename T> struct point;
 // CHECK-NEXT: template <int a, typename T1, typename T2> class third_kernel;
 //
-// CHECK: #include <CL/sycl/detail/kernel_desc.hpp>
-//
 // CHECK: static constexpr
 // CHECK-NEXT: const char* const kernel_names[] = {
 // CHECK-NEXT:   "first_kernel",