cmake: enable_language(OBJC) to fix check_objc_source_compiles().
diff --git a/cmake/macros.cmake b/cmake/macros.cmake
index 914c30f..c284c5e 100644
--- a/cmake/macros.cmake
+++ b/cmake/macros.cmake
@@ -101,6 +101,7 @@ if(${CMAKE_VERSION} VERSION_LESS "3.16.0")
endmacro()
else()
include(CheckOBJCSourceCompiles)
+ enable_language(OBJC)
endif()
if(CMAKE_VERSION VERSION_LESS 3.13.0)