[SYCL] Clean -Wcomment warning (#15064)

Fixes #15063.

Author: aelovikov-intel

sycl/include/sycl/detail/builtins/builtins.hpp

@@ -232,8 +232,8 @@ struct builtin_enable
 // The headers below are specifically implemented without including all the
 // necessary headers to allow preprocessing them on their own and providing
 // human-friendly result. One can use a command like this to achieve that:
-// clang++ -[DU]__SYCL_DEVICE_ONLY__ -x c++ math_functions.inc  \
-//         -I <..>/llvm/sycl/include -E -o - \
+// clang++ -[DU]__SYCL_DEVICE_ONLY__ -x c++ math_functions.inc
+//         -I <..>/llvm/sycl/include -E -o -
 //     | grep -v '^#' | clang-format > math_functions.{host|device}.ii
 
 #include <sycl/detail/builtins/common_functions.inc>