tests: fix build on rpi with EGL
tests: fix build on rpi with EGL

This patch fixes the compiler errors:

  CC     weston_test_la-weston-test.lo
weston-test.c:34:21: fatal error: EGL/egl.h: No such file or directory

  CC     buffer-count-test.o
buffer-count-test.c:30:21: fatal error: EGL/egl.h: No such file or directory

On rpi, the EGL headers are not in the standard path.

Signed-off-by: Pekka Paalanen <0f6ae7001e34c37b02fb2c1c2573ddf8f442136a@collabora.co.uk>

eyolfson/weston,xorgy/weston,Fantu/compositor-spice,mchalupa/weston,Tarnyko/weston-xdg_surface_present,krezovic/weston,giucam/weston,xorgy/weston,eyolfson/weston,kwm81/weston,krezovic/weston,sir-murray/weston,kwm81/weston,Tarnyko/weston-xdg_surface_present,mchalupa/weston,sir-murray/weston,giucam/weston,udoprog/weston,Gnurou/weston,udoprog/weston,jonnylamb/weston,Gnurou/weston,Fantu/compositor-spice,Fantu/compositor-spice,jonnylamb/weston