vmovqdu/vmovqda inline asm doesn't compile on macos catalina

[Peter Maydell]

I just noticed that the recent atomicity changes introduce a build
failure on x86 macos (Catalina). Now if we wanted to, we can say "this
is too old and outside our support policy", of course...
(I don't know if newer x86 macos is OK -- this machine can't
upgrade to anything newer than Catalina. So it's due to be
decommissioned pretty soon anyway.)

In file included from ../../accel/tcg/cputlb.c:1673:
In file included from ../../accel/tcg/ldst_atomicity.c.inc:12:
/Users/pm215/src/qemu/host/include/x86_64/host/load-extract-al16-al8.h:38:13:
error: couldn't allocate output register for constraint 'x'
        asm("vmovdqu %1, %0" : "=x" (r.i) : "m" (*ptr_align));
            ^
/Users/pm215/src/qemu/host/include/x86_64/host/load-extract-al16-al8.h:40:13:
error: couldn't allocate output register for constraint 'x'
        asm("vmovdqa %1, %0" : "=x" (r.i) : "m" (*ptr_align));
            ^
In file included from ../../accel/tcg/cputlb.c:34:
In file included from /Users/pm215/src/qemu/include/qemu/atomic128.h:62:
/Users/pm215/src/qemu/host/include/x86_64/host/atomic128-ldst.h:31:9:
error: couldn't allocate output register for constraint 'x'
    asm("vmovdqa %1, %0" : "=x" (r.i) : "m" (*ptr));
        ^
In file included from ../../accel/tcg/cputlb.c:1673:
In file included from ../../accel/tcg/ldst_atomicity.c.inc:12:
/Users/pm215/src/qemu/host/include/x86_64/host/load-extract-al16-al8.h:38:13:
error: couldn't allocate output register for constraint 'x'
        asm("vmovdqu %1, %0" : "=x" (r.i) : "m" (*ptr_align));
            ^
/Users/pm215/src/qemu/host/include/x86_64/host/load-extract-al16-al8.h:40:13:
error: couldn't allocate output register for constraint 'x'
        asm("vmovdqa %1, %0" : "=x" (r.i) : "m" (*ptr_align));
            ^
In file included from ../../accel/tcg/cputlb.c:34:
In file included from /Users/pm215/src/qemu/include/qemu/atomic128.h:62:
/Users/pm215/src/qemu/host/include/x86_64/host/atomic128-ldst.h:31:9:
error: couldn't allocate output register for constraint 'x'
    asm("vmovdqa %1, %0" : "=x" (r.i) : "m" (*ptr));
        ^
/Users/pm215/src/qemu/host/include/x86_64/host/atomic128-ldst.h:31:9:
error: couldn't allocate output register for constraint 'x'
/Users/pm215/src/qemu/host/include/x86_64/host/atomic128-ldst.h:31:9:
error: couldn't allocate output register for constraint 'x'
/Users/pm215/src/qemu/host/include/x86_64/host/atomic128-ldst.h:55:13:
error: couldn't allocate input reg for constraint 'x'
        asm("vmovdqa %1, %0" : "=m"(*ptr_align) : "x" (new.i));
            ^
In file included from ../../accel/tcg/cputlb.c:1673:
In file included from ../../accel/tcg/ldst_atomicity.c.inc:12:
/Users/pm215/src/qemu/host/include/x86_64/host/load-extract-al16-al8.h:38:13:
error: couldn't allocate output register for constraint 'x'
        asm("vmovdqu %1, %0" : "=x" (r.i) : "m" (*ptr_align));
            ^
/Users/pm215/src/qemu/host/include/x86_64/host/load-extract-al16-al8.h:40:13:
error: couldn't allocate output register for constraint 'x'
        asm("vmovdqa %1, %0" : "=x" (r.i) : "m" (*ptr_align));
            ^
In file included from ../../accel/tcg/cputlb.c:34:
In file included from /Users/pm215/src/qemu/include/qemu/atomic128.h:62:
/Users/pm215/src/qemu/host/include/x86_64/host/atomic128-ldst.h:31:9:
error: couldn't allocate output register for constraint 'x'
    asm("vmovdqa %1, %0" : "=x" (r.i) : "m" (*ptr));
        ^
/Users/pm215/src/qemu/host/include/x86_64/host/atomic128-ldst.h:31:9:
error: couldn't allocate output register for constraint 'x'
13 errors generated.

-- PMM