CMake 2.8.12 compatibility

CMakeLists.txt

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 804d9a0..c3ac1cb 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,7 +3,7 @@
 INCLUDE(GNUInstallDirs)
 
 # ---[ Project
-PROJECT(FXdiv LANGUAGES CXX)
+PROJECT(FXdiv C CXX)
 
 # ---[ Options.
 OPTION(FXDIV_BUILD_TESTS "Build FXdiv unit tests" ON)
@@ -42,7 +42,12 @@
 ENDIF()
 
 # ---[ FXdiv library
-ADD_LIBRARY(fxdiv INTERFACE)
+IF(${CMAKE_VERSION} VERSION_LESS "3.0")
+  ADD_LIBRARY(fxdiv STATIC include/fxdiv.h)
+  SET_TARGET_PROPERTIES(fxdiv PROPERTIES LINKER_LANGUAGE C)
+ELSE()
+  ADD_LIBRARY(fxdiv INTERFACE)
+ENDIF()
 TARGET_INCLUDE_DIRECTORIES(fxdiv INTERFACE include)
 
 INSTALL(FILES include/fxdiv.h DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})