When building against x11-libs/libxcb-1.8-r1, this happens: configure: error: Package requirements (x11 xext xdamage xfixes x11-xcb xcb-glx >= 1.8.1 xxf86vm) were not met: Requested 'xcb-glx >= 1.8.1' but version of XCB GLX is 1.8 The depend shall be therefore changed to require x11-libs/libxcb-1.8.1 or newer. Furtermore, a newer version of libdrm-intel is needed as well: configure: error: Package requirements (libdrm_intel >= 2.4.37) were not met: Requested 'libdrm_intel >= 2.4.37' but version of libdrm is 2.4.34
Fixed in git.