[Bug target/114194] ICE when using std::unique_ptr with xtheadvector

[bruce at hoult dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114194

--- Comment #3 from Bruce Hoult <bruce at hoult dot org> ---
Simpler example, found independently.

    void *memset();
    void a(void *b){ memset(b, 0, 1lu); }

There might be a lot of code that triggers this. Fortunately the source file
this happened in didn't actually use RVV (others did) so I was able to simply
use rv64gc for it.