Add extern "C" to all the headers.

Change-Id: Idc249ff1b199b7c455f90092ff2c8a48b539faf4
diff --git a/minadbd/utils.h b/minadbd/utils.h
index f70ecd2..e833820 100644
--- a/minadbd/utils.h
+++ b/minadbd/utils.h
@@ -16,6 +16,10 @@
 #ifndef _ADB_UTILS_H
 #define _ADB_UTILS_H
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /* bounded buffer functions */
 
 /* all these functions are used to append data to a bounded buffer.
@@ -65,4 +69,8 @@
 #define  BUFF_DECL(_buff,_cursor,_end,_size)   \
     char   _buff[_size], *_cursor=_buff, *_end = _cursor + (_size)
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* _ADB_UTILS_H */