[SYCL] Remove half from global namespace (#4818)

Author: vladimirlaz

sycl/include/CL/sycl/aliases.hpp

@@ -24,9 +24,6 @@ class half;
 } // namespace sycl
 } // __SYCL_INLINE_NAMESPACE(cl)
 
-using half __SYCL2020_DEPRECATED("use 'sycl::half' instead") =
-    cl::sycl::detail::half_impl::half;
-
 #define __SYCL_MAKE_VECTOR_ALIAS(ALIAS, TYPE, N)                               \
   using ALIAS##N = cl::sycl::vec<TYPE, N>;
 

sycl/test/warnings/sycl_2020_deprecations.cpp

@@ -173,9 +173,5 @@ int main() {
   // expected-warning@+1{{'barrier' is deprecated: use 'ext_oneapi_barrier' instead}}
   Queue.submit([&](sycl::handler &CGH) { CGH.barrier(); });
 
-  // expected-warning@+1{{'half' is deprecated: use 'sycl::half' instead}}
-  half H;
-  (void)H;
-
   return 0;
 }