target/i386: port extensions of one-byte opcodes to new decoder

target/i386: port extensions of one-byte opcodes to new decoder

A few two-byte opcodes are simple extensions of existing one-byte opcodes;
they are easy to decode and need no change to emit.c.inc.  Port them to
the new decoder.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>