vbo: increase VBO_SAVE_BUFFER_SIZE from 8k to 256k dwords
vbo: increase VBO_SAVE_BUFFER_SIZE from 8k to 256k dwords

Increases the performance of legacy geometry-heavy apps
still using display lists.

Performance increase for a targeted testcase is on the
order of 8x, and applications like ParaView 4.x (5.x uses
no longer used display lists) improve by about 10%-20%.

Reviewed-by: Mathias Fröhlich <4f933d6351de78dd242eb1149ced32468424a9b8@web.de>
Reviewed-by: Marek Olšák <8c7344a1abdb103e79ecfd488098373070c3c70e@amd.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler