glx: Remove dl_can_open restriction for supports_context_api()
This seems like unnecessary book-keeping which makes the topic
"supported by the display" vs "there is a library that one can manage"
more convoluted than needed.
One can safely assume that if the GLX implementation exposes the
extension(s) then it supports the API. Whether it will succeed in
creating such a context is another topic :)
[chadv: Fix unused variable warning on 'plat']
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Chad Versace <chad.versace@intel.com>