…porary file

Fixed by removing writing key version to start of every block that
was encrypted. Instead we will use single key version from log_sys
crypt info.

After this MDEV also blocks writen to row log are encrypted and blocks
read from row log aren decrypted if encryption is configured for the
table.

innodb_status_variables[], struct srv_stats_t
	Added status variables for merge block and row log block
	encryption and decryption amounts.

Removed ROW_MERGE_RESERVE_SIZE define.

row_merge_fts_doc_tokenize
	Remove ROW_MERGE_RESERVE_SIZE

row_log_t
	Add index, crypt_tail, crypt_head to be used in case of
	encryption.

row_log_online_op, row_log_table_close_func
	Before writing a block encrypt it if encryption is enabled

row_log_table_apply_ops, row_log_apply_ops
	After reading a block decrypt it if encryption is enabled

row_log_allocate
	Allocate temporary buffers crypt_head and crypt_tail
	if needed.

row_log_free
	Free temporary buffers crypt_head and crypt_tail if they
	exist.

row_merge_encrypt_buf, row_merge_decrypt_buf
	Removed.

row_merge_buf_create, row_merge_buf_write
	Remove ROW_MERGE_RESERVE_SIZE

row_merge_build_indexes
	Allocate temporary buffer used in decryption and encryption
	if needed.

log_tmp_blocks_crypt, log_tmp_block_encrypt, log_temp_block_decrypt
	New functions used in block encryption and decryption

log_tmp_is_encrypted
	New function to check is encryption enabled.

Added test case innodb-rowlog to force creating a row log and
verify that operations are done using introduced status
variables.