Add C++ guards to public headers

Fixes #53
Fixes #32

lfs_util.h

@@ -34,6 +34,11 @@
 #include <stdio.h>
 #endif
 
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
 
 // Macros, may be replaced by system specific wrappers. Arguments to these
 // macros must not have side-effects as the macros can be removed for a smaller
@@ -173,5 +178,9 @@ static inline void lfs_free(void *p) {
 }
 
 
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
 #endif
 #endif