patch 8.0.1198: older compilers don't know uint8_t

Problem:    Older compilers don't know uint8_t.
Solution:   Use char_u instead.
diff --git a/src/proto/term.pro b/src/proto/term.pro
index 147981c..ef74f56 100644
--- a/src/proto/term.pro
+++ b/src/proto/term.pro
@@ -64,8 +64,8 @@
 void del_termcode(char_u *name);
 void set_mouse_topline(win_T *wp);
 int check_termcode(int max_offset, char_u *buf, int bufsize, int *buflen);
-void term_get_fg_color(uint8_t *r, uint8_t *g, uint8_t *b);
-void term_get_bg_color(uint8_t *r, uint8_t *g, uint8_t *b);
+void term_get_fg_color(char_u *r, char_u *g, char_u *b);
+void term_get_bg_color(char_u *r, char_u *g, char_u *b);
 char_u *replace_termcodes(char_u *from, char_u **bufp, int from_part, int do_lt, int special);
 int find_term_bykeys(char_u *src);
 void show_termcodes(void);