For a specific grammar used by GMV, ASN1SCC emits LLONG_MIN - which as
per limits.h ...

    #  ifdef __USE_ISOC99

    /* Minimum and maximum values a `signed long long int' can hold.  */
    #   define LLONG_MAX 9223372036854775807LL
    #   define LLONG_MIN (-LLONG_MAX - 1LL)

In plain words, we need -std=c99 during the build.