patch 9.1.1897: Mac: Build failure on Mac OS X 10.6

Problem:  Mac: Build failure on Mac OS X 10.6 due to the use of generics
          for the sound feature.
Solution: Use the simple, non-generic Objective-C version.
          (Luke Lollard)

fixes: #17678
closes: #18681

Co-authored-by: Yee Cheng Chin <ychin.git@gmail.com>
Signed-off-by: Luke Lollard <haihige@protonmail.ch>
Signed-off-by: Christian Brabandt <cb@256bit.org>

Author: 2 people

src/os_macosx.m

@@ -386,7 +386,7 @@
 
 #ifdef FEAT_SOUND
 
-static NSMutableDictionary<NSNumber*, NSSound*> *sounds_list = nil;
+static NSMutableDictionary *sounds_list = nil;
 
 /// A delegate for handling when a sound has stopped playing, in
 /// order to clean up the sound and to send a callback.
@@ -463,9 +463,9 @@ - (void) sound:(NSSound *)sound didFinishPlaying:(BOOL)flag
 
 	if (sounds_list == nil)
 	{
-	    sounds_list = [[NSMutableDictionary<NSNumber*, NSSound*> alloc] init];
+	    sounds_list = [[NSMutableDictionary alloc] init];
 	}
-	sounds_list[[NSNumber numberWithLong:sound_id]] = sound;
+	[sounds_list setObject:sound forKey:[NSNumber numberWithLong:sound_id]];
 
 	// Make a delegate to handle when the sound stops. No need to call
 	// autorelease because NSSound only holds a weak reference to it.
@@ -482,7 +482,7 @@ - (void) sound:(NSSound *)sound didFinishPlaying:(BOOL)flag
 {
     @autoreleasepool
     {
-	NSSound *sound = sounds_list[[NSNumber numberWithLong:sound_id]];
+	NSSound *sound = [sounds_list objectForKey:[NSNumber numberWithLong:sound_id]];
 	if (sound != nil)
 	{
 	    // Stop the sound. No need to release it because the delegate will do

src/version.c

@@ -729,6 +729,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1897,
 /**/
     1896,
 /**/