Created attachment 406488 [details] cdk-5.0.20131107:20150711-053546.log Tries to include `fscale.h` before building it. Compiles fine with MAKEOPTS=-j1.
Created attachment 406490 [details] emerge--info.txt
Can you retry with dev-libs/cdk-5.0.20141106 ?
bug still present with current portage gree : dev-libs/cdk-5.0.20160131