Commit f7df8cc for zlib

commit f7df8cc974c5ca0f2d1ec3a5b93f10dd852973a8
Author: Vollstrecker <werner@vollstreckernet.de>
Date:   Wed Dec 31 10:52:11 2025 +0100

    CMake: Added contrib/infback9.

diff --git a/contrib/CMakeLists.txt b/contrib/CMakeLists.txt
index f5916f3..c3e302a 100644
--- a/contrib/CMakeLists.txt
+++ b/contrib/CMakeLists.txt
@@ -4,6 +4,7 @@ option(ZLIB_BUILD_MINIZIP "Enable building libminizip contrib library" OFF)
 option(ZLIB_WITH_GVMAT64
        "Enable an optiomized longest_match for 32 bits x86_64"
        OFF)
+option(ZLIB_WITH_INFBACK9 "Build with support for method 9 deflate" OFF)

 if(ZLIB_BUILD_ADA)
     set(ZLIBADA_BUILD_SHARED ${ZLIB_BUILD_SHARED})
@@ -29,3 +30,6 @@ endif(ZLIB_BUILD_MINIZIP)
 if(ZLIB_WITH_GVMAT64)
    add_subdirectory(gcc_gvmat64/)
 endif(ZLIB_WITH_GVMAT64)
+if(ZLIB_WITH_INFBACK9)
+   add_subdirectory(infback9/)
+endif(ZLIB_WITH_INFBACK9)
diff --git a/contrib/infback9/CMakeLists.txt b/contrib/infback9/CMakeLists.txt
new file mode 100644
index 0000000..e4bb49e
--- /dev/null
+++ b/contrib/infback9/CMakeLists.txt
@@ -0,0 +1,19 @@
+if(ZLIB_BUILD_SHARED)
+    target_sources(zlib
+        PRIVATE
+            infback9.c
+            inftree9.c
+            infback9.h
+            inffix9.h
+            inftree9.h)
+endif(ZLIB_BUILD_SHARED)
+
+if(ZLIB_BUILD_STATIC)
+    target_sources(zlibstatic
+        PRIVATE
+            infback9.c
+            inftree9.c
+            infback9.h
+            inffix9.h
+            inftree9.h)
+endif(ZLIB_BUILD_STATIC)