Reimplement log_displayBox on macOS.

NSRunCriticalAlertPanel was replaced with the NSAlert class in 10.3
and deprecated in 10.10. This rewrite uses that class instead.

Furthermore, original comments to the contrary, we are not compiling
with ARC and need to actually release the classes we create and allow
for an autorelease pool.

sc2/src/libs/log/msgbox_macosx.m

@@ -21,17 +21,22 @@ void
 log_displayBox (const /*UTF-8*/char *title, int isError,
 		const /*UTF-8*/char *msg)
 {
-	NSString *titleStr = [NSString stringWithUTF8String:title];
-	NSString *msgStr = [NSString stringWithUTF8String:msg];
+	@autoreleasepool {
+		NSAlert *alert = [[NSAlert alloc] init];
+		NSString *titleStr = [NSString stringWithUTF8String:title];
+		NSString *msgStr = [NSString stringWithUTF8String:msg];
 
-	if (!titleStr || !msgStr)
-		return; // Oops, out of memory?
+		if (alert && titleStr && msgStr) {
+			alert.alertStyle = isError ? NSAlertStyleCritical : NSAlertStyleInformational;
+			alert.messageText = titleStr;
+			alert.informativeText = msgStr;
 
-	if (isError)
-		NSRunCriticalAlertPanel (titleStr, @"%@", nil, nil, nil, msgStr);
-	else
-		NSRunInformationalAlertPanel (titleStr, @"%@", nil, nil, nil, msgStr);
+			[alert runModal];
+		}
 
-	// titleStr and msgStr are autoreleased
+		[msgStr release];
+		[titleStr release];
+		[alert release];
+	}
 }