xbps-src: replace basename(1) with ${var##*/}.

Reduce number of fork+exec due to using a subshell to execute basename(1).

common/xbps-src/shutils/update_hash_cache.sh

@@ -6,7 +6,7 @@ update_hash_cache() {
     mkdir -p "$cache"
     find "$XBPS_SRCDISTDIR" -type f | grep -v by_sha256 | while read -r distfile; do
         cksum=$(cat "$distfile" | sha256sum | cut -d " " -f 1)
-        curfile="$(basename ${distfile})"
+        curfile="${distfile##*/}"
         ln -vf "$distfile" "${cache}/${cksum}_${curfile}"
     done
 }