[Bug d/100769] [D] memcmp() == 0 for small constant strings not folded

[witold.baryluk+gcc at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100769

--- Comment #2 from Witold Baryluk <witold.baryluk+gcc at gmail dot com> ---
Hmm. It appears that using `import core.stdc.string : memcmp;` actually
resolves the problem. It looks like my manually declaration of memcmp for some
reason disabled optimisations for memcmp.