math/dgl: fix build with clang 19
Clang 19 now implements CWG 96 [1], which requires a template argument
list after a 'template' keyword, resulting in errors similar to:
/wrkdirs/usr/ports/math/dgl/work/dgl-1.1.2/third_party/tensorpipe/third_party/libnop/include/nop/types/variant.h:241:30: error: a template argument list is expected after a name prefixed by the template keyword [-Wmissing-template-arg-list-after-template-kw]
241 | index_ = value_.template Construct(std::forward<Args>(args)...);
| ^
/wrkdirs/usr/ports/math/dgl/work/dgl-1.1.2/third_party/tensorpipe/third_party/libnop/include/nop/types/variant.h:258:26: error: a template argument list is expected after a name prefixed by the template keyword [-Wmissing-template-arg-list-after-template-kw]
258 | if (!value_.template Assign(TypeTag<T>{}, index_, std::forward<U>(value))) {
| ^
/wrkdirs/usr/ports/math/dgl/work/dgl-1.1.2/third_party/tensorpipe/third_party/libnop/include/nop/types/variant.h:265:26: error: a template argument list is expected after a name prefixed by the template keyword [-Wmissing-template-arg-list-after-template-kw]
265 | if (!value_.template Assign(index_, std::forward<T>(value))) {
| ^In all these cases, appending "<>" is enough to satisfy the constraint.
[1] https://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#96
PR: 282949
Approved by: maintainer timeout (2 weeks)
MFH: 2024Q4
(cherry picked from commit 4dc6727cb525f1252c5483cf80a691fd5bbeb49d)