Adjust egl config.test to pass sysrooted libs

We should really start using -L=/foo and -I=/foo inside of sysroots,

this test was preventing us from doing so (while arguably buying us
nothing).

Change-Id: If6e67631c585493871231e5d8a9354fa72e07343
Reviewed-by: Laszlo Agocs <laszlo.agocs@theqtcompany.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>