libtiff: Fix including module getopt.c twice with CMake and HAVE_GETOPT=false

SDL Commits
1 
From d1d87635f1ae5036185938847f2b026bdee2f9af Mon Sep 17 00:00:00 2001
From: Su_Laus <[EMAIL REDACTED]>
Date: Sat, 20 Aug 2022 19:33:45 +0200
Subject: [PATCH] Fix including module getopt.c twice with CMake and
 HAVE_GETOPT=false

The "make-files" for the tools- and test- programmes include the module getopt.c once directly as additional source and then again by including port.lib.
This can be avoided by including getopt.c as source in port.lib within port\CMakeLists.txt not with PUBLIC but with PRIVATE.
---
 port/CMakeLists.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/port/CMakeLists.txt b/port/CMakeLists.txt
index 04bd3ea8..d03fc3f0 100755
--- a/port/CMakeLists.txt
+++ b/port/CMakeLists.txt
@@ -35,7 +35,7 @@ if(NOT HAVE_GETOPT)
 
   # Add getopt if missing
   if(NOT HAVE_GETOPT)
-    target_sources(tiff_port PUBLIC
+    target_sources(tiff_port PRIVATE
             ${CMAKE_CURRENT_SOURCE_DIR}/getopt.c)
   endif()