`_Alignof [expression]` behavior with array types

[fuhsnn]

This is a GCC extension; for arrays it reports alignment of the variable instead of the element type

#include <stdio.h>
int main(int argc, char** argv) {
    char _Alignas(1024) arr1[11];
    char _Alignas(1024) arr2[argc];
    printf("%d\n", _Alignof arr1); // gcc/clang: 1024 chibicc: 1
    printf("%d\n", _Alignof arr2); // gcc/clang: 1024 chibicc: 8

    printf("%d\n", _Alignof *&arr1); // gcc:1024 clang:1
}