[XeTeX] Support request for /Rotate in pdf

[Akira Kakuto]

> We don't get any warnings in inclusion of pdf which has /Rotate: XeTeX
> says nothing, and xdvipdfmx says nothing because default output-driver
> is 'xdvipdfmx -q -E' in TL2015. I think this is harmful, because there is no
> chance for users to notice unrotated figures before they see output directly.
> At least in TL2014 xdvipdfms shows warning like
> "<< /Rotate 90 >> found. (not supported yet)"

Jonathan had decided the default option of the driver
xdvipdfmx to be '-q -E'. In TL 2014, the option -q (quiet)
was not complete. In TL2015, the option -q is improved to
be really quiet. If some messages are prefered, the -q
option may be removed: xdvipdfmx -E.
In this case,

xdvipdfmx:warning: << /Rotate 90 >> found. (Not supported yet)

is shown if /Rotate command is found.

Thanks,
Akira