Change assembler to use byte instruction lengths

Change the Arm & Mips instruction templaces to record instruction
size in bytes rather than half-words.  Also includes a few Mips
changes to get us in compilable state.

Change-Id: I5a4f6cbd0cb0569805d9dfbd341c244152e59ac7
diff --git a/src/compiler/codegen/mips/MipsLIR.h b/src/compiler/codegen/mips/MipsLIR.h
index 93956d5..9baa3c0 100644
--- a/src/compiler/codegen/mips/MipsLIR.h
+++ b/src/compiler/codegen/mips/MipsLIR.h
@@ -547,7 +547,7 @@
     int flags;
     const char *name;
     const char* fmt;
-    int size;
+    int size;     /* Size in bytes */
 } MipsEncodingMap;
 
 /* Keys for target-specific scheduling and other optimization hints */