[DefKorns]

For 2.1.0.

• FD_CLOEXEC: scripts started by the menu inherited its open files, /dev/fb0 included, so uistop (from chmenu, uistart, a folder switch) killed them. MarkFdsCloseOnExec() (src/framework/close_on_exec.*) marks every fd >= 3 close-on-exec right before each system(), popen() and fork+exec in options, save_manager and mod_uninstall. The menu keeps using its fds. The lifecycle's signal handler is left alone.
• omLoading [key...]: gen_splash --loading now takes the line keys, and draws them with the moving bar until the calling script exits ("Loading" without keys). The Wi-Fi backup splash uses it.
• omReloadMenu shows the splash while the UI is stopped, instead of a black screen. With omReloadMenuLater it keeps the caller's text, so add-ons show one splash from start to finish.

Tested on the console (SNES Classic, Super Famicom firmware):

• A child of system() inherited 16 fds with the old binary (/dev/fb0, /dev/mali, /dev/input/event*, /dev/tty0-1), and only its own with the new one.
• A script started from the menu ran omReloadMenu (uistop + chmenu) to the end and the home menu came back, with the Loading splash.
• Menus and submenus, toggles and choice rows, command logs, a download, Save Manager, Module Uninstaller, and the Favorites save and reload.
• tests/run_tests.sh: 27/27 and 11/11. Plain and compat builds.