Use shared CUPTI by default
Per https://github.com/pytorch/pytorch/issues/57744 statically linked CUPTI
causes exception handling to break on certain compiler configurations, likely
because CUPTI comes with incompatible libstdc++ symbols. Rather than pray that
something reasonable happens, use the safer configuration (dynamic linking) by
default and give a warning if the user inverts the setting.
Signed-off-by: Edward Z. Yang <ezyangfb.com>