patch 9.1.0581: Various lines are indented inconsistently

Problem:  style: Various lines are indented inconsistently
Solution: Retab these lines and correct some comments.
          (zeertzjq)

closes: #15259

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/getchar.c

@@ -2036,8 +2036,8 @@ vgetc(void)
 		vgetc_char = c;
 	    }
 
-	    // a keypad or special function key was not mapped, use it like
-	    // its ASCII equivalent
+	    // A keypad or special function key was not mapped, use it like
+	    // its ASCII equivalent.
 	    switch (c)
 	    {
 		case K_KPLUS:	c = '+'; break;