Fix kipiplugins fallout

[tcberner]

Summary

The update of kdelibs broke the way linker flags are passed.
Import the fix from area51 r12727.

Test Plan

It worked in area51 for 9 months... so it should work.
That being said, poudriere looks fine so far too =)

[tcberner]

Oh, just saw rakuco is already on it.

[rakuco]

I've fixed it differently in rP437106.