bindings: force the first letter in a key name to uppercase

So that converting it to a key code remains easy.

This fixes https://savannah.gnu.org/bugs/?57655.

Bug existed since commit 077d307b from yesterday.

src/rcfile.c

@@ -719,8 +719,11 @@ void parse_binding(char *ptr, bool dobind)
 	ptr = parse_next_word(ptr);
 	keycopy = copy_of(keyptr);
 
-	/* Force the first character of the key name to uppercase. */
-	keycopy[0] = toupper((unsigned char)keycopy[0]);
+	/* Uppercase either the second or the first character of the key name. */
+	if (keycopy[0] == '^')
+		keycopy[1] = toupper((unsigned char)keycopy[1]);
+	else
+		keycopy[0] = toupper((unsigned char)keycopy[0]);
 
 	/* Verify that the key name is not too short, to allow the next call. */
 	if (keycopy[1] == '\0' || (keycopy[0] == 'M' && keycopy[2] == '\0')) {