st/clover: add space between < and ::

st/clover: add space between < and ::

As pointed out by compiler

./llvm/codegen.hpp:52:22: error: ‘<::’ cannot begin a template-argument list [-fpermissive]
./llvm/codegen.hpp:52:22: note: ‘<:’ is an alternate spelling for ‘[’. Insert whitespace between ‘<’ and ‘::’

Cc: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>
Reviewed-by: Vedran Miletić <vedran@miletic.net>