Build failure in fixincludes on x86_64

[Gerald Pfeifer]

On Wed, 26 May 2021, Richard Earnshaw via Gcc wrote:
>> ../../git/gcc/fixincludes/fixtests.c: In function ‘run_test’:
>> ../../git/gcc/fixincludes/fixtests.c:155:1: internal compiler error:
>> in operator[], at vec.h:890
>>   155 | }
>>       | ^
> Same failure on arm.

Same failure on x86 (32-bit, i586-unknown-freebsd11.4).

Gerald