dix: add dixAddAtom()

Convenient helper function for creating atom and get it's ID.
If atom already exist, the existing ID is retrieved.

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>

dix/dix_priv.h

@@ -704,6 +704,18 @@ static inline int WriteRpcbufToClient(ClientPtr pClient,
     return ret;
 }
 
+/*
+ * @brief make atom from null-terminated string
+ *
+ * if atom already existing, return the existing Atom ID
+ *
+ * @param name  the atom name
+ * @return atom ID
+ */
+static inline Atom dixAddAtom(const char *name) {
+    return MakeAtom(name, strlen(name), TRUE);
+}
+
 /*
  * @brief retrieve atom ID by name
  *