[Bug target/96494] [nvptx] Enable effective target sync_int_long

[vries at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96494

--- Comment #2 from Tom de Vries <vries at gcc dot gnu.org> ---
FTR, we could fix this by just mapping onto a nonatomic insn for .local (and
I'm not really sure why ptx doesn't).

But since we have generic pointers, we only known runtime whether something is
local (using isspacep), so that while that will help the standalone target be
more generic, it'll possibly make the offloading target slower and larger.