add of_str64_t string type
We need a 64-byte string for the debug_counter extension. Since adding a new
string type is so much work, the new type is named generically so that any
extension can use it.
diff --git a/c_gen/c_code_gen.py b/c_gen/c_code_gen.py
index 10668b7..81f5a1a 100644
--- a/c_gen/c_code_gen.py
+++ b/c_gen/c_code_gen.py
@@ -700,6 +700,7 @@
typedef char of_table_name_t[OF_MAX_TABLE_NAME_LEN];
typedef char of_desc_str_t[OF_DESC_STR_LEN];
typedef char of_serial_num_t[OF_SERIAL_NUM_LEN];
+typedef char of_str64_t[64];
typedef struct of_bitmap_128_s {
uint64_t hi;