releasetools: Make blockimgdiff.py pylint-clean.

************* Module blockimgdiff
C:433, 0: Unnecessary parens after 'if' keyword (superfluous-parens)
C:687, 0: Wrong hanging indentation (add 4 spaces).
            max_stashed_blocks, self._max_stashed_size, max_allowed,
            ^   | (bad-continuation)
C:688, 0: Wrong hanging indentation (add 4 spaces).
            self._max_stashed_size * 100.0 / max_allowed))
            ^   | (bad-continuation)
C:691, 0: Wrong hanging indentation (remove 2 spaces).
            max_stashed_blocks, self._max_stashed_size))
          | ^ (bad-continuation)
C:898, 0: Wrong hanging indentation (add 4 spaces).
                  "imgdiff" if imgdiff else "bsdiff",
                  ^   | (bad-continuation)
C:899, 0: Wrong hanging indentation (add 4 spaces).
                  xf.tgt_name if xf.tgt_name == xf.src_name else
                  ^   | (bad-continuation)
C:901, 0: Wrong hanging indentation (add 4 spaces).
                  xf.tgt_ranges, xf.src_ranges, e.message))
                  ^   | (bad-continuation)
C:909, 0: Wrong hanging indentation (add 4 spaces).
                      xf.tgt_name,))
                      ^   | (bad-continuation)
C:917, 0: Wrong hanging indentation (add 4 spaces).
                      xf.tgt_name, e.message))
                      ^   | (bad-continuation)
C:961, 0: Wrong hanging indentation (remove 2 spaces).
                xf.patch_len, tgt_size, xf.patch_len * 100.0 / tgt_size,
              | ^ (bad-continuation)
C:962, 0: Wrong hanging indentation (remove 2 spaces).
                xf.style,
              | ^ (bad-continuation)
C:963, 0: Wrong hanging indentation (remove 2 spaces).
                xf.tgt_name if xf.tgt_name == xf.src_name else (
              | ^ (bad-continuation)
C:965, 0: Wrong hanging indentation (remove 2 spaces).
                xf.tgt_ranges, xf.src_ranges))
              | ^ (bad-continuation)
C:1422, 0: Wrong continued indentation (add 28 spaces).
                tgt_skipped.size() * 100.0 / tgt_size, tgt_name))
                ^                           | (bad-continuation)
C:1560, 0: Wrong continued indentation (add 8 spaces).
            split_src_ranges) in enumerate(split_info_list):
            ^       | (bad-continuation)
R:566, 6: Redefinition of src_str type from list to str (redefined-variable-type)
C:1198,25: More than one statement on a single line (multiple-statements)
C:1211,25: More than one statement on a single line (multiple-statements)
C:1220,16: More than one statement on a single line (multiple-statements)
C:1277,38: More than one statement on a single line (multiple-statements)
C:1284,19: More than one statement on a single line (multiple-statements)
C: 19, 0: standard import "import copy" comes before "import common" (wrong-import-order)
C: 20, 0: standard import "import functools" comes before "import common" (wrong-import-order)
C: 21, 0: standard import "import heapq" comes before "import common" (wrong-import-order)
C: 22, 0: standard import "import itertools" comes before "import common" (wrong-import-order)
C: 23, 0: standard import "import multiprocessing" comes before "import common" (wrong-import-order)
C: 24, 0: standard import "import os" comes before "import common" (wrong-import-order)
C: 25, 0: standard import "import os.path" comes before "import common" (wrong-import-order)
C: 26, 0: standard import "import re" comes before "import common" (wrong-import-order)
C: 27, 0: standard import "import subprocess" comes before "import common" (wrong-import-order)
C: 28, 0: standard import "import sys" comes before "import common" (wrong-import-order)
C: 29, 0: standard import "import threading" comes before "import common" (wrong-import-order)
C: 31, 0: standard import "from collections import deque, OrderedDict" comes before "import common" (wrong-import-order)
C: 32, 0: standard import "from hashlib import sha1" comes before "import common" (wrong-import-order)

Test: `pylint --rcfile=pylintrc blockimgdiff.py`
Test: Generate an incremental BBOTA package.
Change-Id: Ia7ecd0e1fa48daf4e43251bdcdfcd08fb316015d