Switch to aapt2 for getting minSdkVersion

aapt does not support parsing some referencing attributes.
Switch to latest tool, aapt2, which works better.

Test: aapt2 dump badging test.apk and returned 0.
Test: Run check_target_files_signatures.py with a target_files.zip.
Test: Run sign_target_files_apks.py with a target_files.zip.
Change-Id: Ib3a4740506f29ebab6930767f2aa8a0b5c4ba053
diff --git a/tools/releasetools/check_target_files_signatures.py b/tools/releasetools/check_target_files_signatures.py
index 60200a3..8c1bb9a 100755
--- a/tools/releasetools/check_target_files_signatures.py
+++ b/tools/releasetools/check_target_files_signatures.py
@@ -213,7 +213,7 @@
     self.certs = frozenset(out)
 
   def ReadManifest(self, full_filename):
-    p = common.Run(["aapt", "dump", "xmltree", full_filename,
+    p = common.Run(["aapt2", "dump", "xmltree", full_filename, "--file",
                     "AndroidManifest.xml"],
                    stdout=subprocess.PIPE)
     manifest, err = p.communicate()