GLX_USE_TLS

[nia <nia%NetBSD.org@localhost>]

The recent thread indicating GLX_USE_TLS breaks static linking
remided me it's disabled for pkgsrc Mesa. The reasons for this are
likely something only I care about - having it enabled caused random
segfaults on startup for applications that used Mesa outside X11,
and turning it off seemed the path of least headaches.

The recent project to upstream FreeBSD support in Mesa took a similar
approach of simply disabling TLS usage. It seems that TLS support
in Mesa is (a) an optimization only, not needed for any functionality,
and (b) broken on essentially everything that isn't Linux-with-glibc
(Linux distributions using musl libc have also disabled it outright).

In xsrc we've taken a different approach of patching around problems,
but there are still evidently bugs left.

I'm curious whether there's anyone in NetBSD who's strongly attached
to TLS in libGL, and what their reasoning is. To me, it seems like
having it turned off is the easiest way to avoid bugs without
maintaining local patches that hack around random crashes and other
TLS-induced problems.