patch 8.2.2830: terminal colors are not updated when 'background' is set

Problem:    Terminal colors are not updated when 'background' is set.
Solution:   Call term_update_colors() for all terminals. (Marcin Szamotulski,
            closes #8171, closes #8150)
diff --git a/src/proto/terminal.pro b/src/proto/terminal.pro
index f3bd5a3..d2e5992 100644
--- a/src/proto/terminal.pro
+++ b/src/proto/terminal.pro
@@ -19,6 +19,7 @@
 int term_use_loop(void);
 void term_win_entered(void);
 int terminal_loop(int blocking);
+void set_terminal_default_colors(int cterm_fg, int cterm_bg);
 int may_close_term_popup(void);
 void term_channel_closed(channel_T *ch);
 void term_check_channel_closed_recently(void);
@@ -28,10 +29,10 @@
 int term_show_buffer(buf_T *buf);
 void term_change_in_curbuf(void);
 int term_get_attr(win_T *wp, linenr_T lnum, int col);
-void term_update_colors(void);
+void term_update_colors(term_T *term);
+void term_update_colors_all(void);
 char_u *term_get_status_text(term_T *term);
 int set_ref_in_term(int copyID);
-void set_terminal_default_colors(int cterm_fg, int cterm_bg);
 void f_term_dumpwrite(typval_T *argvars, typval_T *rettv);
 int term_swap_diff(void);
 void f_term_dumpdiff(typval_T *argvars, typval_T *rettv);