JIT: Use vmla.f64 instead of vmuld + vaddd.

Optimize Java double floating-point performance for ARM JIT.
Whenever a double mul is followed with a double add,
replace it with a combined mul and add instruction.

This improves double arithmetic performance for code executing
in Dalvik.

Change-Id: Ia4fccf4fa53aa9fb4a76cbf388f5ea16dcef32b7
Signed-off-by: Patrik Ryd <patrik.ryd@stericsson.com>
Revert "JIT: Use vmla.f64 instead of vmuld + vaddd."

This reverts commit 9a67197393e136b6086526fefd45cb341080e1e1.
Revert "Revert "JIT: Performance fix for const doubles""

This reverts commit 6799723387fe725e5418a83d2762539530a8835c.
Fix JIT bug related to immediate doubles

Change 256211 (JIT: Performance Fix for const doubles) introduced a
defect that can cause the JIT to use the wrong floating point
double constant in traces in which the following conditions hold:

   o Two (or more) different 64-bit floating point constants are used.
   o The physical register holding the first constant is still live
     at the time the second constant is used.
   o The low 32 bits of the two constants are identical.

In this situation, the load/copy optimization pass will incorrectly
determine that the two constants are the same, delete the load of
the second constant and re-use the first constant value.

Note: this problem only occurs with 64-bit floating point literals.
64-bit long literals are unaffected.

This CL works around the problem, and a subsequent CL will rework
disambiguation of 64-bit immediates in a somewhat cleaner fashion.

(cherry-pick of c1757a6deab0ca0bfd42c38612d92b2f26c41dbe.)

Change-Id: I795b4b753550d2745cbbdd83ae25f4a7088990f6