patch 8.1.2382: MS-Windows: When using VTP bold+inverse doesn't work

Problem:    MS-Windows: When using VTP bold+inverse doesn't work.
Solution:   Compare with the default colors. (Nobuhiro Takasaki, closes #5303)
diff --git a/src/proto/os_win32.pro b/src/proto/os_win32.pro
index 94b2f72..e60ce92 100644
--- a/src/proto/os_win32.pro
+++ b/src/proto/os_win32.pro
@@ -71,6 +71,7 @@
 void set_alist_count(void);
 void fix_arg_enc(void);
 int mch_setenv(char *var, char *value, int x);
+void get_default_console_color(int *cterm_fg, int *cterm_bg, guicolor_T *gui_fg, guicolor_T *gui_bg);
 void control_console_color_rgb(void);
 int use_vtp(void);
 int is_term_win32(void);