[SYCL] Add a static_assert/check that app and sycl use consistent C++ RT on win

SYCL library is designed such a way that STL objects must cross the sycl.dll
boundary, which is guaranteed to work safe on Windows only if the runtime
in the app using sycl.dll and in sycl.dll is the same and is dynamic.

It is not possible to implement safe approach for using sycl libraries
built/linked with static C++ RT as it would cause having multiple copies
of C++ objects (such as scheduler, etc), which are supposed to be
singletones.

This check reports a compile-time error when user tries to compile
the application using sycl.dll with /MT or /MTd switches implying
using static C++ runtime libcmt[d].lib.

sycl.dll is built with /MD and sycld.dll is built with /MDd.
Thus /MD and /MDd are allowed, and /MT /MTd switches are prohibited now.

Author: v-klochkov

sycl/include/CL/sycl/stl.hpp

@@ -22,6 +22,27 @@
 __SYCL_INLINE_NAMESPACE(cl) {
 namespace sycl {
 
+#ifdef _WIN32
+namespace detail {
+// SYCL library is designed such a way that STL objects cross DLL boundary,
+// which is not guaranteed to work and considered not safe.
+// Using same dynamic C++ runtime library for sycl[d].dll and for
+// the application using sycl[d].dll is guaranteed to work properly.
+inline constexpr bool isMSVCDynamicCXXRuntime() {
+// The options /MD and /MDd that make the code to use dynamic runtime also
+// define the _DLL macro.
+#ifdef _DLL
+  return true;
+#else
+  return false;
+#endif
+}
+static_assert(isMSVCDynamicCXXRuntime(),
+              "SYCL library is designed to work with dynamic C++ runtime, "
+              "please use /MD or /MDd switches.");
+} // namespace detail
+#endif // _WIN32
+
  template < class T, class Alloc = std::allocator<T> >
  using vector_class = std::vector<T, Alloc>;