[2.2] workaround for gcc 14 incompatible pointer types

[crazy-max]

relates to https://github.com/crazy-max/docker-alpine-s6/actions/runs/11092390584/job/30817368677#step:10:38837

 > [linux/arm/v7 builder 25/48] RUN ./configure     --enable-shared     --enable-static     --disable-allstatic     --prefix=/usr     --libdir=/usr/lib   && make install -j$(nproc)   && make DESTDIR=/dist install -j$(nproc)   && tree /dist:
30.91 src/skaembutils/s6-expr.c:84:33: error: passing argument 2 of 'int32_scan_base' from incompatible pointer type [-Wincompatible-pointer-types]
30.91    84 |       if (!long_scan(argv[pos], &tree[pos].data)) bail() ;
30.91       |                                 ^
30.91       |                                 |
30.91       |                                 long int *
30.92 /usr/include/skalibs/uint32.h:62:46: note: expected 'int32_t *' {aka 'int *'} but argument is of type 'long int *'
30.92    62 | extern size_t int32_scan_base (char const *, int32_t *, uint8_t) ;
30.92       |                                              ^~~~~~~~~
31.54 make: *** [Makefile:132: src/skaembutils/s6-expr.o] Error 1
31.54 make: *** Waiting for unfinished jobs....