Snippets for libisoburn 1.5.8 from Alpine aarch64

Sourced from https://build.alpinelinux.org/buildlogs/build-edge-aarch64/main/libisoburn/libisoburn-1.5.8-r0.log.

• xorriso/iso_img.c:290:8: warning: taking the absolute value of unsigned type 'char' has no effect [-Wabsolute-value]
    290 |    at= abs(pvd_time[16]);
        |        ^~~