add C++ guards in unity.h

src/unity.h

@@ -8,6 +8,11 @@
 #define UNITY_FRAMEWORK_H
 #define UNITY
 
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
 #include "unity_internals.h"
 
 //-------------------------------------------------------
@@ -271,4 +276,7 @@
 #define TEST_ASSERT_DOUBLE_IS_NOT_DETERMINATE_MESSAGE(actual, message)                             UNITY_TEST_ASSERT_DOUBLE_IS_NOT_DETERMINATE((actual), __LINE__, (message))
 
 //end of UNITY_FRAMEWORK_H
+#ifdef __cplusplus
+}
+#endif
 #endif