CBMC fails to parse constructor attribute with argument

[archigup]

CBMC parses non-argument constructor attributes correctly but fails to parse them when they have an argument.

Steps to reproduce:

test.c:

__attribute__((constructor(101))) void foo(void) {
}

int main(void) {
}

output:

$ cbmc test.c 
CBMC version 6.7.1 (n/a) 64-bit x86_64 linux
file test.c line 1: syntax error before '('
PARSING ERROR
6$ 

I think it would be fine if CBMC ignored the argument and treated it the same way as constructor without an argument (would be fine for all of our use cases at least).