engines/Makefile.in: some [older] shell complain about 'for i ;', but not if there is reference to empty variable.
engines/Makefile.in: some [older] shell complain about 'for i ;',
but not if there is reference to empty variable.

Reviewed-by: Richard Levitte <5fb523282dd7956571c80524edc2dccfa0bd8234@openssl.org>

openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl