CMake: Support cmake down to 2.8.5

CMakeLists.txt

 set(CMAKE_LEGACY_CYGWIN_WIN32 0)
-cmake_minimum_required(VERSION 2.8)
+cmake_minimum_required(VERSION 2.8.5)
 
 include(GNUInstallDirs)
 
@@ -172,8 +172,12 @@ if(ENABLE_CJSON_TEST)
 
     # Disable -fsanitize=float-divide-by-zero for cJSON_test
     if (FLAG_SUPPORTED_fsanitizefloatdividebyzero)
+        if ("${CMAKE_VERSION}" VERSION_LESS "2.8.12")
+            set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fno-sanitize=float-divide-by-zero")
+        else()
             target_compile_options(${TEST_CJSON} PRIVATE "-fno-sanitize=float-divide-by-zero")
         endif()
+    endif()
 
     if(ENABLE_CJSON_UTILS)
         set(TEST_CJSON_UTILS cJSON_test_utils)

tests/CMakeLists.txt

@@ -3,12 +3,20 @@ if(ENABLE_CJSON_TEST)
 
     # Disable -Werror for Unity
     if (FLAG_SUPPORTED_Werror)
+        if ("${CMAKE_VERSION}" VERSION_LESS "2.8.12")
+            set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-error")
+        else()
             target_compile_options(unity PRIVATE "-Wno-error")
         endif()
+    endif()
     # Disable -fvisibility=hidden for Unity
     if (FLAG_SUPPORTED_fvisibilityhidden)
+        if ("${CMAKE_VERSION}" VERSION_LESS "2.8.12")
+            set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fvisibility=default")
+        else()
             target_compile_options(unity PRIVATE "-fvisibility=default")
         endif()
+    endif()
 
     #copy test files
     file(MAKE_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/inputs")