target/mips: optimize cross-page direct jumps in softmmu

Cc: Yongbok Kim <yongbok.kim@imgtec.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Message-Id: <20170430145254.25616-3-aurelien@aurel32.net>
Signed-off-by: Richard Henderson <rth@twiddle.net>