Fix eabi calling convention when a 64 bit value shadows r3.
Fix eabi calling convention when a 64 bit value shadows r3.

Without this what was happening was:

* R3 is not marked as "used"
* ARM backend thinks it has to save it to the stack because of vaarg
* Offset computation correctly ignores it
* Offsets are wrong

git-svn-id: a4a6f32337ebd29ad4763b423022f00f68d1c7b7@110446 91177308-0d34-0410-b5e6-96231b3b80d8

lodyagin/bare_cxx,lodyagin/bare_cxx,lodyagin/bare_cxx,lodyagin/bare_cxx,lodyagin/bare_cxx