relocate applypatch; add type system and new functions to edify

- Move applypatch to this package (from build).

- Add a rudimentary type system to edify:  instead of just returning a
  char*, functions now return a Value*, which is a struct that can
  carry different types of value (currently just STRING and BLOB).
  Convert all functions to this new scheme.

- Change the one-argument form of package_extract_file to return a
  Value of the new BLOB type.

- Add read_file() to load a local file and return a blob, and
  sha1_check() to test a blob (or string) against a set of possible
  sha1s.  read_file() uses the file-loading code from applypatch so it
  can read MTD partitions as well.

This is the start of better integration between applypatch and the
rest of edify.

b/2361316 - VZW Issue PP628: Continuous reset to Droid logo:
            framework-res.apk update failed (CR LIBtt59130)

Change-Id: Ibd038074749a4d515de1f115c498c6c589ee91e5
diff --git a/applypatch/imgdiff.h b/applypatch/imgdiff.h
new file mode 100644
index 0000000..f2069b4
--- /dev/null
+++ b/applypatch/imgdiff.h
@@ -0,0 +1,30 @@
+ * Copyright (C) 2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+// Image patch chunk types
+#define CHUNK_NORMAL   0
+#define CHUNK_GZIP     1   // version 1 only
+#define CHUNK_DEFLATE  2   // version 2 only
+#define CHUNK_RAW      3   // version 2 only
+// The gzip header size is actually variable, but we currently don't
+// support gzipped data with any of the optional fields, so for now it
+// will always be ten bytes.  See RFC 1952 for the definition of the
+// gzip format.
+#define GZIP_HEADER_LEN   10
+// The gzip footer size really is fixed.
+#define GZIP_FOOTER_LEN   8