st/mesa: use table-driven approach to exposing extensions based on CAPs

st/mesa: use table-driven approach to exposing extensions based on CAPs

This change is not exactly equivalent (sometimes we checked for non-zero,
sometimes if >0 or >1), but the behavior shouldn't change, because all drivers
report 0 for unsupported CAPs.

Exposing CAP_STREAM_OUTPUT_PAUSE_RESUME without CAP_MAX_STREAM_OUTPUT_BUFFERS
is a driver bug and st/mesa does no checking if the latter is supported as
well. Drivers must report CAPs consistently.

v2: make the array const