Add vmov between floating point registers to ARM assembler.

Add vmov between floating point registers to ARM assembler.

Adds generating binary versions of vmov for moves between floating
point registers, in the integrated ARM assembler.

Also adds simple lit test. Also simplifies the lit test for push/pop
(which had to be changed anyway since it included vmov instructions as
well).

BUG= https://bugs.chromium.org/p/nativeclient/issues/detail?id=4334
R=eholk@chromium.org, jpp@chromium.org

Review URL: https://codereview.chromium.org/1645683003 .