CMake: Fix the Ada standalone build.

contrib/ada/CMakeLists.txt

diff --git a/contrib/ada/CMakeLists.txt b/contrib/ada/CMakeLists.txt
index 8922200..b7a2e4d 100644
--- a/contrib/ada/CMakeLists.txt
+++ b/contrib/ada/CMakeLists.txt
@@ -5,7 +5,7 @@
 project(
     zlibAda
     VERSION 1.0.0
-    LANGUAGES ADA
+    LANGUAGES C ADA
     DESCRIPTION "A library for creating zipfiles based in zlib"
     HOMEPAGE_URL "https://www.zlib.net")