Adapt to removal of BitcodeSuffix in libomptarget...

This should fix:

```
RPM build errors:
    absolute symlink: /usr/bin/clang-format-diff ->
/usr/share/clang/clang-format-diff.py
    File not found:
/builddir/build/BUILD/llvm-20.0.0_pre20241225.g34f8573a514915-build/BUILDROOT/usr/lib64/libomptarget-amdgpu-*.bc
    File not found:
/builddir/build/BUILD/llvm-20.0.0_pre20241225.g34f8573a514915-build/BUILDROOT/usr/lib64/libomptarget-nvptx-*.bc
```

See
llvm/llvm-project@34f8573#diff-c89ebf1fc950679f63c19739a35aa966a12674f7d61af6fb382ab1fa0ee21dd7L2842

Author: kwk

llvm.spec

@@ -2726,8 +2726,13 @@ fi
 # libomptarget is not supported on 32-bit systems.
 # s390x does not support the offloading plugins.
 %{install_libdir}/libomptarget.devicertl.a
+%if %{maj_ver} >= 20
+%{install_libdir}/libomptarget-amdgpu*.bc
+%{install_libdir}/libomptarget-nvptx*.bc
+%else
 %{install_libdir}/libomptarget-amdgpu-*.bc
 %{install_libdir}/libomptarget-nvptx-*.bc
+%endif
 %{install_libdir}/libomptarget.so
 %if %{maj_ver} >= 20
 %{install_libdir}/libLLVMOffload.so