patch 8.2.1015: popup filter gets key with modifier prepended

Problem:    Popup filter gets key with modifier prepended when using
            modifyOtherKeys.
Solution:   Remove the shift modifier when it is included in the key, also
            when the Alt or Meta modifier is used.
diff --git a/src/misc2.c b/src/misc2.c
index 41b9f71..649cb65 100644
--- a/src/misc2.c
+++ b/src/misc2.c
@@ -2929,9 +2929,11 @@
     if ((modifiers & MOD_MASK_SHIFT) && ASCII_ISALPHA(key))
     {
 	key = TOUPPER_ASC(key);
-	// With <C-S-a> and <A-S-a> we keep the shift modifier.
-	// With <S-a> and <S-A> we don't keep the shift modifier.
-	if (simplify || modifiers == MOD_MASK_SHIFT)
+	// With <C-S-a> we keep the shift modifier.
+	// With <S-a>, <A-S-a> and <S-A> we don't keep the shift modifier.
+	if (simplify || modifiers == MOD_MASK_SHIFT
+		|| modifiers == (MOD_MASK_SHIFT | MOD_MASK_ALT)
+		|| modifiers == (MOD_MASK_SHIFT | MOD_MASK_META))
 	    modifiers &= ~MOD_MASK_SHIFT;
     }