The include file <command.h> does not need anything from <env.h>.
Furthermore, include/env.h itself includes other headers which can lead
to longer indirect inclusion paths. To prepare to remove <env.h> from
<command.h> fix all of the places which had relied on this indirect
inclusion to instead include <env.h> directly.
Reviewed-by: Mattijs Korpershoek <mkorpershoek@kernel.org> # android, bcb
Reviewed-by: Jerome Forissier <jerome.forissier@linaro.org> # spawn
Signed-off-by: Tom Rini <trini@konsulko.com>