util: Fixes thread safety of DEBUG_GET_ONCE_*_OPTION macros

util: Fixes thread safety of DEBUG_GET_ONCE_*_OPTION macros

Pick DEBUG_GET_ONCE_BOOL_OPTION as a example:
The intention of DEBUG_GET_ONCE_BOOL_OPTION are returned the same value across
thread, before this commit, on different thread call the function generated by
DEBUG_GET_ONCE_BOOL_OPTION may return different value if called setenv in the
middle of debug_get_bool_option, so use debug_get_option_cached along with
new exposed function debug_parse_bool_option to solve this issue

Signed-off-by: Yonggang Luo <luoyonggang@gmail.com>
Acked-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/19554>