tools/envcrc: fix compile breakage

When ENV_IS_EMBEDDED is not set, but CONFIG_BUILD_ENVCRC is set,
the environment.h file does not get included resulting in unrecognized
env_t type.
Fix this by moving the include directive.

Reported-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Igor Grinberg <grinberg@compulab.co.il>
Tested-by: Mike Frysinger <vapier@gentoo.org>