MDEV-18637 Assertion `cache' failed in fts_init_recover_doc

I know no test case for this bug in 10.1. So a test case will be
committed separately in 10.2

fts_reset_get_doc(): properly initialize fts_get_doc_t::cache

storage/innobase/fts/fts0fts.cc

 /*****************************************************************************
 
 Copyright (c) 2011, 2018, Oracle and/or its affiliates. All Rights Reserved.
-Copyright (c) 2016, 2018, MariaDB Corporation.
+Copyright (c) 2016, 2019, MariaDB Corporation.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -736,6 +736,7 @@ fts_reset_get_doc(
 		memset(get_doc, 0x0, sizeof(*get_doc));
 
 		get_doc->index_cache = ind_cache;
+		get_doc->cache = cache;
 	}
 
 	ut_ad(ib_vector_size(cache->get_docs)
@@ -4801,8 +4802,9 @@ fts_tokenize_document(
 	ut_a(!doc->tokens);
 	ut_a(doc->charset);
 
-	doc->tokens = rbt_create_arg_cmp(
-                                         sizeof(fts_token_t), innobase_fts_text_cmp, (void*) doc->charset);
+	doc->tokens = rbt_create_arg_cmp(sizeof(fts_token_t),
+					 innobase_fts_text_cmp,
+					 (void*) doc->charset);
 
 	for (ulint i = 0; i < doc->text.f_len; i += inc) {
 		inc = fts_process_token(doc, result, i, 0);

storage/xtradb/fts/fts0fts.cc

 /*****************************************************************************
 
 Copyright (c) 2011, 2018, Oracle and/or its affiliates. All Rights Reserved.
-Copyright (c) 2016, 2018, MariaDB Corporation.
+Copyright (c) 2016, 2019, MariaDB Corporation.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -567,7 +567,7 @@ fts_index_cache_init(
 
 	index_cache->words = rbt_create_arg_cmp(
 		sizeof(fts_tokenizer_word_t), innobase_fts_text_cmp,
-		(void*)index_cache->charset);
+		(void*) index_cache->charset);
 
 	ut_a(index_cache->doc_stats == NULL);
 
@@ -736,6 +736,7 @@ fts_reset_get_doc(
 		memset(get_doc, 0x0, sizeof(*get_doc));
 
 		get_doc->index_cache = ind_cache;
+		get_doc->cache = cache;
 	}
 
 	ut_ad(ib_vector_size(cache->get_docs)
@@ -2004,7 +2005,8 @@ fts_create_one_index_table(
 	dict_mem_table_add_col(new_table, heap, "ilist", DATA_BLOB,
 			       4130048,	0);
 
-	error = row_create_table_for_mysql(new_table, trx, false, FIL_ENCRYPTION_DEFAULT, FIL_DEFAULT_ENCRYPTION_KEY);
+	error = row_create_table_for_mysql(new_table, trx, false,
+		FIL_ENCRYPTION_DEFAULT, FIL_DEFAULT_ENCRYPTION_KEY);
 
 	if (error != DB_SUCCESS) {
 		trx->error_state = error;
@@ -4800,8 +4802,9 @@ fts_tokenize_document(
 	ut_a(!doc->tokens);
 	ut_a(doc->charset);
 
-	doc->tokens = rbt_create_arg_cmp(
-		sizeof(fts_token_t), innobase_fts_text_cmp, (void*) doc->charset);
+	doc->tokens = rbt_create_arg_cmp(sizeof(fts_token_t),
+					 innobase_fts_text_cmp,
+					 (void*) doc->charset);
 
 	for (ulint i = 0; i < doc->text.f_len; i += inc) {
 		inc = fts_process_token(doc, result, i, 0);