media-libs/openimageio: fix various minor issues

[waebbl]

• change one pkg spec in metadata.xml from media-libs/openvdb to media-gfx/openvdb
• remove ssl and libressl USE flags. I didn't found any trace for dependencies on SSL. Also comment the argument to cmake for SSL.
• change USE dep default for doxygen[latex], due to new version no longer ships this USE flag
• add openimageio.pdf to DOCS only when USE=doc is present and the file is actually built
• add '|| die' to sed statements in src_prepare. Also add missing '\' chars to some of them to ensure proper expanding
• change -DUSE_OCIO to -DUSE_OpenColorIO. The former has caused a warning in cmake for a defined but unused variable

Signed-off-by: Bernd Waibel waebbl@gmail.com

Note: I didn't resolve various fatal errors from older versions reported by repoman full, therefore commited directly via git and not repoman.