lib/pattern: Fix seg fault when calculating pattern length

lib/pattern: Fix seg fault when calculating pattern length

When --buffer_pattern or --verify_pattern has multiple elements
(0x110x22 or 0xdeadface"abcd"-12'filename') calculating the length
produces a segmentation fault in parse_and_fill_pattern() because it
increments out when out is passed to the parse_* routines it calls.

This patch uses the fix provided in the GitHub issue.

Fixes: https://github.com/axboe/fio/issues/1500
Fixes: 6c9397396eb83a6ce64a998795e7a50552e4337e "lib/pattern: Support
NULL output buffer in parse_and_fill_pattern()"

Signed-off-by: Vincent Fu <vincent.fu@samsung.com>