use 'lib/pattern' to parse patterns and paste formats into buffers

use 'lib/pattern' to parse patterns and paste formats into buffers

Switch to new 'lib/pattern' helpers.

Now 'buffer_pattern' and 'verify_pattern' options support combined input
and strings like:

 buffer_pattern="1234"0xface"5678"
 verify_pattern=0xface"1234"-12+14

can be specified.

Also, 'verify_pattern' supports '%o' format, which means that buffer will
be patched on each iteration with real 'block offset' number.

So, f.e. 'verify_pattern' such combined input is valid:

 verify_pattern=%o

 or

 verify_pattern=%o"123"%o

Signed-off-by: Roman Pen <r.peniaev@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>