anv: Store CPU-side fence information in the BO
anv: Store CPU-side fence information in the BO

This reduces the number of allocations a bit and cuts back on memory usage.
Kind-of a micro-optimization but it also makes the error handling a bit
simpler so it seems like a win.

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler