x86 interrupt calling convention: only save xmm registers if the target supports SSE

The existing code always saves the xmm registers for 64-bit targets even if the
target doesn't support SSE (which is common for kernels). Thus, the compiler
inserts movaps instructions which lead to CPU exceptions when an interrupt
handler is invoked.

This commit fixes this bug by returning a register set without xmm registers
from getCalleeSavedRegs and getCallPreservedMask for such targets.

Patch by Philipp Oppermann.

Differential Revision: https://reviews.llvm.org/D29959

llvm-svn: 295347