Added more checking upon resolution and bytecode rewriting to verifier.

Access checks are performed when methods and fields are resolved. Also,
erroring bytecodes are now overwritten in the memory mapped dex file.
To do this, the code sets the memory mapped dex file as writable before
verification and set it back to read only after verification is done.
The overwritting occurs only in memory and the original dex file remains
unchanged.

Change-Id: I054394fb57e83d1ac5b6f200ab993d70cd9f55e6
diff --git a/src/dex_instruction.h b/src/dex_instruction.h
index 3934d7d..e08a1f7 100644
--- a/src/dex_instruction.h
+++ b/src/dex_instruction.h
@@ -32,6 +32,7 @@
     k11n,  // op vA, #+B
     k11x,  // op vAA
     k10t,  // op +AA
+    k20bc, // op AA, kind@BBBB
     k20t,  // op +AAAA
     k22x,  // op vAA, vBBBB
     k21t,  // op vAA, +BBBB