aux/vbuf: add some vroom
This changes redundant buffer updates to no-ops inside vbuf for massive performance gains.
drawoverhead results (zink on nvidia don't judge me):
test 5: 1 vertex attrib change - ~11% improvement
before: 
after: 
test 6: 16 vertex attribs change - ~55% improvement
before: 
after: 
test 7: shader program change - ~3% improvement
before: 
after: 
Edited by Mike Blumenkrantz