The use of env is not needed, and caused the output makefile to be
created in some setups where it was not supposed to.
Seems to be an issue with GNU sh-utils version of env.

One user also reported env to be located in another place (/usr/local/bin/..).
This patch fixes bug: http://bugme.osdl.org/show_bug.cgi?id=3953

Thanks to "Mark Williams (MWP)" <mwp@internode.on.net> for helping tracking this down.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>