[libxslt] Set project language to C

[Nick Wellnhofer <nwellnhof src gnome org>]

commit 0129fe422474d9f259f0a0545fb3bae21536d0c1
Author: Markus Rickert <rickert fortiss org>
Date:   Sun Jul 12 18:40:57 2020 +0200

    Set project language to C

 CMakeLists.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6b952b2f..645abe9c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 3.12)
 
-project(libxslt1)
+project(libxslt1 C)
 
 include(CheckCSourceCompiles)
 include(CheckFunctionExists)