glx: add fail check for current context in another thread

glx: add fail check for current context in another thread

The GLX spec for glXMakeCurrent (3.3):
"If ctx is current to some other thread, then glXMakeCurrent will generate
a BadAccess error"

The GLX spec for glXCopyContext (3.3):
"If the destination context is current for some thread then a BadAccess
error is generated"

Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/7961
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Illia Polishchuk <illia.a.polishchuk@globallogic.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22546>