scons: Put to rest zombie texture_float build option.

I found a remnant of texture_float build option that wasn't removed in
commit 66673bef941af344314fe9c91cad8cd330b245eb

This patch removes it.

Cc: mesa-stable@lists.freedesktop.org
Reviewed-by: Jose Fonseca <jfonseca@vmware.com>
1 file changed