CMake: Enable C so cmake/graphviz does not fail

CMake/templates/CMakeLists_bin.txt

 project({project_name}
 	VERSION {alib_versioning_major}.{alib_versioning_minor}.{alib_versioning_patch}
-	LANGUAGES CXX)
+	LANGUAGES C CXX)
 set(PROJECT_NAME {project_name})
 find_package(tclap REQUIRED)

CMake/templates/CMakeLists_itest.txt

 project({project_name}
 	VERSION {alib_versioning_major}.{alib_versioning_minor}.{alib_versioning_patch}
-	LANGUAGES CXX)
+	LANGUAGES C CXX)
 set(PROJECT_NAME_TEST test-{project_name})
 {cmake_options}

CMake/templates/CMakeLists_lib.txt

 project({project_name}
 	VERSION {alib_versioning_major}.{alib_versioning_minor}.{alib_versioning_patch}
-	LANGUAGES CXX)
+	LANGUAGES C CXX)
 set(PROJECT_NAME {project_name})
 {cmake_options}

CMake/templates/CMakeLists_root.txt

@@ -2,7 +2,7 @@ cmake_minimum_required(VERSION 3.7)
 project(alib2
 	VERSION {alib_versioning_major}.{alib_versioning_minor}.{alib_versioning_patch}
-	LANGUAGES CXX)
+	LANGUAGES C CXX)
 set(CMAKE_MODULE_PATH ${{CMAKE_SOURCE_DIR}}/CMake/Modules)
 set(CONFIGURE_HEADERS_SRC_DIR ${{CMAKE_SOURCE_DIR}}/CMake/headers)