build: Fix the Win32 platform test for GLES2
build: Fix the Win32 platform test for GLES2

The error message has a small typo (copy and paste from the GLES1
detection code) and the check was reversed.

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