[Bug target/118813] [14/15 regression] avx512bwintrin.h is not `-Wsystem-headers -Wundef` clean since r14-4490-g03a8504815d539

[haochen.jiang at intel dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118813

--- Comment #11 from Haochen Jiang <haochen.jiang at intel dot com> ---
It should be #ifdef instead of #if here from my first glance.