[Sycl][Graph] Remove SYCL_EXPORT from template to fix build error

[fabiomestre]

PR #16788 broke the windows post-commit CI when building with icx/icpx https://github.com/intel/llvm/actions/runs/13310637099/job/37172065867

D:\github\_work\llvm\llvm\build\include\sycl\ext\oneapi\experimental\graph.hpp(577,8): error: 'dllexport' attribute ignored [-Werror,-Wignored-attributes]
  577 | struct __SYCL_EXPORT
      |        ^
D:\github\_work\llvm\llvm\build\include\sycl\detail\export.hpp(23,34): note: expanded from macro '__SYCL_EXPORT'
   23 | #define __SYCL_EXPORT __declspec(dllexport)
      |                                  ^
In file included from D:\github\_work\llvm\llvm\src\sycl\unittests\Extensions\EventMode.cpp:9:
In file included from D:\github\_work\llvm\llvm\build\include\sycl\sycl.hpp:11:
In file included from D:\github\_work\llvm\llvm\build\include\sycl\detail\core.hpp:23:
In file included from D:\github\_work\llvm\llvm\build\include\sycl\queue.hpp:34:
D:\github\_work\llvm\llvm\build\include\sycl\ext\oneapi\experimental\graph.hpp(587,8): error: 'dllexport' attribute ignored [-Werror,-Wignored-attributes]
  587 | struct __SYCL_EXPORT
      |        ^
D:\github\_work\llvm\llvm\build\include\sycl\detail\export.hpp(23,34): note: expanded from macro '__SYCL_EXPORT'
   23 | #define __SYCL_EXPORT __declspec(dllexport)
      |                                  ^
2 errors generated.

Fix by not exporting these symbols

[aelovikov-intel]

@fabiomestre , looks like the build passed in https://github.com/intel/llvm/actions/runs/13313100130/job/37180396241.

Are you ok with merging this? We can do that without waiting for the full testing to finish to fix post-commit. We'd need @intel/sycl-graphs-reviewers approval though.

[fabiomestre]

@fabiomestre , looks like the build passed in https://github.com/intel/llvm/actions/runs/13313100130/job/37180396241.

Are you ok with merging this? We can do that without waiting for the full testing to finish to fix post-commit. We'd need @intel/sycl-graphs-reviewers approval though.

Yeah, feel free to go ahead and merge it 👍 . Konrad from our team has approved it.