gen-egg-recipes: generate recipes using class-cross override
gen-egg-recipes: generate recipes using class-cross override

Use class-cross instead of virtclass-cross override.

The virtclass-cross override has been removed (see
03a0f8e8b4e286bfcc0076e7380ce26d1b1b106a in poky).

Signed-off-by: Mario Domenech Goulart <addb47291ee169f330801ce73520b96f2eaf20ea@ossystems.com.br>

OSSystems/meta-chicken,OSSystems/meta-chicken,OSSystems/meta-chicken