[llvm] [SYCL] Add libsycl, a SYCL RT library implementation project (PR #144372)

[Kseniya Tikhomirova via llvm-commits]

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@@ -0,0 +1,19 @@
+{
+  /* Do not use extern "C++" matcher for C++ functions,                     */
+  /* because vtable and typeinfo symbols make extern "C++" patterns more    */
+  /* complicated than patterns against mangled names.                       */
+  /*                                                                        */
+  /* With extern "C++" we have to match for "vtable for sycl::foo", but */
+  /* not match for "vtable for std::__internal<sycl::foo>".             */
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KseniyaTikhomirova wrote:

will update, thanks

https://github.com/llvm/llvm-project/pull/144372