Use RETURN_PTR(NULL) instead of RETURN_VOID in newNonMovableArray.

RETURN_VOID doesn't set the return value. This means that we are
returning random garbage when the allocation doesn't succeed.

Bug: 11971220
Change-Id: I570562c7bb9dc573161294916f582709774b35fd
Remove some ARMv5 cruft.

Change-Id: I95dcfd9dff8db25b9419b8ef862e3b9b70927a0c
Remove the sole reference to __ARM_HAVE_BLX.

Every ARM processor we run on has blx.

Change-Id: I633984d208d8a1995b9595521352e0b16413837c