patch 8.1.1513: all popup functionality is in functions, except :popupclear

Problem:    All popup functionality is in functions, except :popupclear.
Solution:   Add popup_clear() for consistency.  Also rename sound_stopall() to
            sound_clear().
diff --git a/src/proto/popupwin.pro b/src/proto/popupwin.pro
index a50e7b7..2a377a7 100644
--- a/src/proto/popupwin.pro
+++ b/src/proto/popupwin.pro
@@ -1,5 +1,6 @@
 /* popupwin.c */
 void popup_adjust_position(win_T *wp);
+void f_popup_clear(typval_T *argvars, typval_T *rettv);
 void f_popup_create(typval_T *argvars, typval_T *rettv);
 void f_popup_atcursor(typval_T *argvars, typval_T *rettv);
 int popup_any_visible(void);
@@ -9,7 +10,6 @@
 void popup_close(int id);
 void popup_close_tabpage(tabpage_T *tp, int id);
 void close_all_popups(void);
-void ex_popupclear(exarg_T *eap);
 void f_popup_move(typval_T *argvars, typval_T *rettv);
 void f_popup_getpos(typval_T *argvars, typval_T *rettv);
 void f_popup_getoptions(typval_T *argvars, typval_T *rettv);
diff --git a/src/proto/sound.pro b/src/proto/sound.pro
index 43e4727..cf8439a 100644
--- a/src/proto/sound.pro
+++ b/src/proto/sound.pro
@@ -2,6 +2,6 @@
 void f_sound_playevent(typval_T *argvars, typval_T *rettv);
 void f_sound_playfile(typval_T *argvars, typval_T *rettv);
 void f_sound_stop(typval_T *argvars, typval_T *rettv);
-void f_sound_stopall(typval_T *argvars, typval_T *rettv);
+void f_sound_clear(typval_T *argvars, typval_T *rettv);
 void sound_free(void);
 /* vim: set ft=c : */