I am trying to build Evas_generic_loaders which are a part of E17.
An optional requirement is LibRaw support which is enabled by default but inspite of LibRaw and LibRaw-devel being present, it is not getting picked up during the build because log shows this line :
It appears that LibRaw-devel is not storing it's pkg-config file in the right place so the configure process can't find it

It is storing it in /usr/include/pkconfig whereas PCLOS uses /usr/lib/pkgconfig.
Until this is changed/corrected you could try adding the following before the %configure2_5x:
export PKG_CONFIG_PATH=$PKG_CONFIG_PATH:%{_includedir}/pkgconfigTerry.