[PATCH 2.25] powerpc: Avoid calling strncmp via PLT on GCC 7

[Florian Weimer]

* Tulio Magno Quites Machado Filho:

> +/* GCC 7.0 added support for a builtin strncmp that is used on POWER >= 7.  */
> +#if !defined __ASSEMBLER__ && IS_IN (libc) && defined SHARED \
> +    && defined _ARCH_PWR7
> +asm ("strncmp = __GI_strncmp");
> +#endif

Would it be safe to do this unconditionally, in the generic header?