target-alpha: Avoid gcc 6.1 werror for linux-user

target-alpha: Avoid gcc 6.1 werror for linux-user

Using gcc 6.1 for alpha-linux-user target we see the following build error:

.../target-alpha/translate.c: In function ‘in_superpage’:
.../target-alpha/translate.c:454:52: error: self-comparison always evaluates to true [-Werror=tautological-compare]
             && addr >> TARGET_VIRT_ADDR_SPACE_BITS == addr >> 63);

Reported-by: Pranith Kumar <[email protected]>
Signed-off-by: Richard Henderson <[email protected]>
Message-id: 1466192793[email protected]
Signed-off-by: Peter Maydell <[email protected]>