[Bug middle-end/85420] More -Wrestrict false positives with -fsanitize=undefined

[sirl at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85420

--- Comment #3 from Franz Sirl <sirl at gcc dot gnu.org> ---
Hmm, this maybe creduce'd too much, the original source reads more like

   strcpy(b, b + a + 10);

which would be only UB for sure if strlen(b + a + 10) >= 9, or?