Emit the prologue/epilogue using frame offsets.

Emit the prologue/epilogue using frame offsets.

Record register save offsets in ix86_frame.

Move SP/FP offsets into the global state; update them everywhere
we currently handle CFA offsets.

Use that global state to choose base registers and offsets for
the register saves and restores.

There is a bug fix contained herein, whereby r11 could be clobbered
along an indirect sibcall path when the stack frame is very large (>2GB).
The emit_restore_{sse_,}regs_using_mov functions didn't handle this
case, but pro_epilogue_adjust_stack does.

From-SVN: r162888