target/arm: Align vector registers

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

target/arm/cpu.h

@@ -492,7 +492,7 @@ typedef struct CPUARMState {
          * the two execution states, and means we do not need to explicitly
          * map these registers when changing states.
          */
-        uint64_t regs[64];
+        uint64_t regs[64] QEMU_ALIGNED(16);
 
         uint32_t xregs[16];
         /* We store these fpcsr fields separately for convenience.  */