Update language to comply with Android’s inclusive language guidance

See https://source.android.com/setup/contribute/respectful-code for reference

 #inclusivefixit

Bug: 161896447
Test: N/A
Change-Id: I9fd970726d739da658f6419a1ccd3e4952b17c78

tools/releasetools/blockimgdiff.py

@@ -521,7 +521,7 @@ class BlockImageDiff(object):
         stashed_blocks -= free_size
 
       if common.OPTIONS.cache_size is not None:
-        # Sanity check: abort if we're going to need more stash space than
+        # Validation check: abort if we're going to need more stash space than
         # the allowed size (cache_size * threshold). There are two purposes
         # of having a threshold here. a) Part of the cache may have been
         # occupied by some recovery logs. b) It will buy us some time to deal