Tweak bin chmod

Chmod on the symlink seems to work just fine (at least on Linux) but I
think chmod on the source might be safer.

Author: code-asher

ci/build/npm-postinstall.sh

@@ -56,12 +56,13 @@ symlink_bin_script() {
   case $OS in
     windows)
       ext=".cmd"
-      symlink "$source.cmd" "$dest$ext"
+      source="$source.cmd"
       ;;
-    darwin | macos) symlink "$source-darwin.sh" "$dest$ext" ;;
-    *) symlink "$source-linux.sh" "$dest$ext" ;;
+    darwin | macos) source="$source-darwin.sh" ;;
+    *) source="$source-linux.sh" ;;
   esac
-  chmod +x "$dest$ext"
+  chmod +x "$source"
+  symlink "$source" "$dest$ext"
   cd "$oldpwd"
 }