meson.build: Order the flex/bison by odds of them working

meson.build: Order the flex/bison by odds of them working

Some flex/bison installs on windows include yacc and lex
as bash scripts that call bison/flex binaries. That creates
an extra layer of dependencies because those won't work from
plain cmd.exe/powershell. Lets switch the lookup order so that
by default we pickup vanilla binaries instead of scripts.

Reviewd-by: Charmaine Lee <charmainel@vmware.com>
Reviewed-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Reviewed-by: Jose Fonseca <jfonseca@vmware.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7806>