I had dri2proto-2.2 installed and ebuilding xorg-server-1.9.0 failed with: checking for DRI... yes checking for DRI2PROTO... no configure: error: DRI2 requested, but dri2proto not found. Upgrading to x11-proto/dri2proto-2.3 fixed the problem. Reproducible: Always Steps to Reproduce:
Fixed in main tree. Thx for report.