gallium/postprocessing: fix shader parsing
gallium/postprocessing: fix shader parsing

tokens was converted to a pointer, which made the Elements macro return 1.

Broken by e87fc11cac696881469a57955af2ac7b4929a2c7.

Cc: 59f39c0db42d4479a46b02d4d2bc11120e37bb44@lists.freedesktop.org
Reviewed-by: Kenneth Graunke <bd2562f754ec92342f93f61c25d731e290a2ffa8@whitecape.org>
Reviewed-by: Brian Paul <3cb4e1df5ec4da2c7c4af7c52cec8cf340a55a10@vmware.com>

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