Centralize instruction-set pointer-size, alignment, 64b-width code
in instruction_set.h/cc

This allows to clean up some places that currently make explicit
comparisons.

Change-Id: I0dcc924c52fa53306f706aceea93a2d4a655c5df
diff --git a/compiler/dex/frontend.cc b/compiler/dex/frontend.cc
index 201dc47..1bf5fce 100644
--- a/compiler/dex/frontend.cc
+++ b/compiler/dex/frontend.cc
@@ -158,7 +158,7 @@
   if (cu.instruction_set == kArm) {
     cu.instruction_set = kThumb2;
   }
-  cu.target64 = (cu.instruction_set == kX86_64) || (cu.instruction_set == kArm64);
+  cu.target64 = Is64BitInstructionSet(cu.instruction_set);
   cu.compiler = compiler;
   // TODO: x86_64 & arm64 are not yet implemented.
   CHECK((cu.instruction_set == kThumb2) ||
@@ -166,7 +166,6 @@
         (cu.instruction_set == kX86_64) ||
         (cu.instruction_set == kMips));
 
-
   /* Adjust this value accordingly once inlining is performed */
   cu.num_dalvik_registers = code_item->registers_size_;
   // TODO: set this from command line