build: cogl-clip-state.h depends on cogl-clip-stack.h
build: cogl-clip-state.h depends on cogl-clip-stack.h

This adds a #include "cogl-clip-stack.h" to cogl-clip-state.h which
depends on the CoglClipStack typedef.

djdeath/cogl,spatulasnout/cogl,djdeath/cogl-android,djdeath/cogl,Distrotech/cogl,gcampax/cogl,spatulasnout/cogl,Distrotech/cogl,gcampax/cogl,Distrotech/cogl,gcampax/cogl,djdeath/cogl-android,djdeath/cogl,gcampax/cogl,Distrotech/cogl,collects/cogl,collects/cogl,djdeath/cogl-android