shutils/pkgtarget: speed up build dir cleanup.

We need `chmod -R` to be able to cleanup after Go packages, but it's
unnecessary in most other cases. By only running it when the first `rm
-rf` fails, we optimize for the most common case and get a tiny speedup
for this build step.

common/xbps-src/shutils/pkgtarget.sh

@@ -79,7 +79,7 @@ remove_pkg_autodeps() {
 remove_pkg_wrksrc() {
     if [ -d "$wrksrc" ]; then
         msg_normal "$pkgver: cleaning build directory...\n"
-        chmod -R +wX "$wrksrc" # Needed to delete Go Modules
+        rm -rf "$wrksrc" || chmod -R +wX "$wrksrc" # Needed to delete Go Modules
         rm -rf "$wrksrc"
     fi
 }