patch 9.1.0611: ambiguous mappings not correctly resolved with modifyOtherKeys

Problem:  ambiguous mappings not correctly resolved with modifyOtherKeys
Solution: Check for termcode when an upper case mapping is received and
          does not match (Oleg Goncharov)

Fix for mapping processing when capital leters are represented with terminal codes.

Problem: there are two mappings and
1) the first mapping is substring of the second,
2) the first non-matching letter is capital,
3) capital letters are represented with termcodes "ESC[27;2;<ascii code>~" in given system
then first mapping is applied instead of second.

Example:

    :map B b
    :map BBB blimp!

and then

    BBB -> bbb

instead of

    BBB -> blimp!

Solution: force termcodes check if capital letter does not match.

closes: #15251

Signed-off-by: Oleg Goncharov <goncharovoi@yandex.ru>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/view_util.vim b/src/testdir/view_util.vim
index 71cb071..161c8b2 100644
--- a/src/testdir/view_util.vim
+++ b/src/testdir/view_util.vim
@@ -71,7 +71,7 @@
 " than the raw code.
 
 " Return the modifyOtherKeys level 2 encoding for "key" with "modifier"
-" (number value, e.g. CTRL is 5).
+" (number value, e.g. CTRL is 5, Shift is 2, Alt is 3).
 func GetEscCodeCSI27(key, modifier)
   let key = printf("%d", char2nr(a:key))
   let mod = printf("%d", a:modifier)