input: don’t allow non-significant modifiers when matching untranslated symbols

When matching “untranslated” bindings (by matching the base symbol of
the key, e.g. ctrl+shift+2 in US layout), require that no
non-significant modifiers are active.

This fixes an issue where AltGr was “ignored”, and would cause certain
combinations to match a key binding.

Example: ctrl+altgr+0, on many European layouts matched against the
default ctrl+0 (reset the font size), instead of emitting ^]

To make this work, we now need to filter out “locked”
modifiers (e.g. NumLock and CapsLock). Otherwise having e.g. NumLock
active would prevent *all* untranslated matching to fail.

Closes #983

url-mode.h

@@ -21,5 +21,6 @@ void urls_reset(struct terminal *term);
 
 void urls_input(struct seat *seat, struct terminal *term, uint32_t key,
                 xkb_keysym_t sym, xkb_mod_mask_t mods, xkb_mod_mask_t consumed,
+                xkb_mod_mask_t locked,
                 const xkb_keysym_t *raw_syms, size_t raw_count,
                 uint32_t serial);