pass blobs to applypatch in incremental OTAs

applypatch now takes patches as blob-valued arguments instead of just
filenames, eliminating the need to unpack all patches to /tmp before
starting to apply them.

Revert the last change I made where sha1_check(read_file(...)) was
substituted for apply_patch_check(...).  apply_patch_check() knows to
check /cache/saved.file if the original source file is missing or has
a bad checksum, which is important if the device loses power or
otherwise restarts during patching.

Change-Id: Ia5b761474b0f809a5a5eed29455b1b145145699e

tools/releasetools/both_generator.py

@@ -41,6 +41,7 @@ class BothGenerator(object):
   def AssertSomeBootloader(self, *a): self._DoBoth("AssertSomeBootloader", *a)
   def ShowProgress(self, *a): self._DoBoth("ShowProgress", *a)
   def PatchCheck(self, *a): self._DoBoth("PatchCheck", *a)
+  def FileCheck(self, filename, *sha1): self._DoBoth("FileCheck", *a)
   def CacheFreeSpaceCheck(self, *a): self._DoBoth("CacheFreeSpaceCheck", *a)
   def Mount(self, *a): self._DoBoth("Mount", *a)
   def UnpackPackageDir(self, *a): self._DoBoth("UnpackPackageDir", *a)