patch 8.2.0936: some terminals misinterpret the code for getting cursor style

Problem:    Some terminals misinterpret the code for getting cursor style.
Solution:   Send a sequence to the terminal and check the result. (IWAMOTO
            Kouichi, closes #2126)  Merged with current code.
diff --git a/src/proto/term.pro b/src/proto/term.pro
index 88fdcb8..40934ea 100644
--- a/src/proto/term.pro
+++ b/src/proto/term.pro
@@ -47,7 +47,7 @@
 void starttermcap(void);
 void stoptermcap(void);
 void may_req_termresponse(void);
-void may_req_ambiguous_char_width(void);
+void check_terminal_behavior(void);
 void may_req_bg_color(void);
 int swapping_screen(void);
 void scroll_start(void);