./configure --prefix=/usr --with-dri-driverdir=/usr/lib/xorg/modules/dri --with-gallium-drivers=r300,r600,nouveau,svga,swrast --enable-gallium-llvm --enable-gallium-egl --enable-shared-glapi --enable-glx-tls --enable-dri --enable-glx --enable-osmesa --enable-gles1 --enable-gles2 --enable-egl --enable-texture-float --enable-xa --enable-shared-dricore
When compiling mesa with osmesa and --enable-shared-glapi, OpenGL functions such as glNormal3f, glVertex3f, etc. are not defined in libOSMesa but are defined in libGL. It would be good if there was an option to build libOSMesa with static GL API and the rest built with shared GL API at the same time. This means if libGL is replaced with a proprietary libGL, libOSMesa can still continue to function properly.
Created attachment 82036 [details]
I have no idea how much this helps, but give it a shot..