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

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

common/hooks/pre-pkg/06-shlib-provides.sh

@@ -13,7 +13,7 @@ collect_sonames() {
 
 	# real pkg
 	find ${_destdir} -type f -name "*.so*" | while read f; do
-		_fname=$(basename "$f")
+		_fname="${f##*/}"
 		case "$(file -bi "$f")" in
 		application/x-sharedlib*)
 			# shared library