*.sh: drop useless use of "env"

In a bourne shell script, "VAR=VAL command" is sufficient to run
'command' with environment variable VAR set to value VAL without
affecting the environment of the shell itself; there is no need
to say "env VAR=VAL command".

Signed-off-by: Junio C Hamano <gitster@pobox.com>
Merge branch 'jc/no-need-for-env-in-sh-scripts' into pu

* jc/no-need-for-env-in-sh-scripts:
  *.sh: drop useless use of "env"