util: fix new gcc6 warnings
util: fix new gcc6 warnings

src/util/hash_table.h:111:23: warning: ‘_mesa_fnv32_1a_offset_bias’ defined but not used [-Wunused-const-variable]
 static const uint32_t _mesa_fnv32_1a_offset_bias = 2166136261u;
                       ^~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Rob Clark <915c10c999604870200b6defbe633d857c856ca0@gmail.com>
Reviewed-by: Ian Romanick <2b237cafb16dc45038e85df6c85e74e6d899eba9@intel.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler