fix(relinker): write Linux and macOS executables with execute permission

The executables were written with the default file mode (0644 under a
022 umask). The documented chmod covered app.elf, but not the outputs of
--executable, so RetroArch (PPSA99169) converted with
--executable picker/picker.bin --executable es-de/es-de.bin stopped as
soon as it started its picker:

  sceSystemServiceLoadExec: execv failed: Permission denied

Every executable output now gets execute permission for owner, group and
others after it is written, as --autorun already did for app.elf. With
it RetroArch starts the picker, and the picker starts ES-DE.

core/relinker/main.cpp

@@ -194,6 +194,11 @@ int Run(const int argc, char* argv[]) {
         }
         for (const auto& executable : executables) {
             fileWriter.Write(executable.OutputPath, executable.Bytes);
+            if (!args.toWindows) {
+                std::error_code error;
+                std::filesystem::permissions(Io::NativePath(executable.OutputPath), std::filesystem::perms::owner_exec | std::filesystem::perms::group_exec | std::filesystem::perms::others_exec, std::filesystem::perm_options::add, error);
+                if (error) throw Domain::RelinkerException("Cannot make the output executable: " + executable.OutputPath + " (" + error.message() + ")");
+            }
             progress.Report({Domain::ProgressStage::Write, absPath, ++written, outputCount});
         }
         if (args.writeRegistry) {