CMake OpenImage library not found

[tartarini]

Despite passing explicitly the location of the library, pFire's CMake doesn't pickup the library and reports missing optional oiio library

/usr/bin/cmake3 ../ -DPETSC_EXECUTABLE_RUNS=yes -DDCMTK_DIR=/home/tartarini/local/libs/DCMTK/3.6.5/ -DCMAKE_INSTALL_PREFIX=/home/tartarini/local/dev/pfire/v0.5.0/ -DOpenImageIO_ROOT=/home/tartarini/local/libs/oiio/2.3.0.1/ -DOPENIMAGEIO_ROOT_DIR=/home/tartarini/local/libs/oiio/2.3.0.1/