DARWIN: make growlagent build not run afoul of ._ fun

DARWIN: make growlagent build not run afoul of ._ fun

in some cases a git checkout would promptly merge the ._ file away,
meaning a subsequent build would fail. just use the developer tools
to set an icon instead of clever tricks.

(cherry picked from commit 0ef3ce2006b81f590c62a51b7ec903ebff24b9c8)
Reviewed-on: http://gerrit.openafs.org/3563
Tested-by: Derrick Brashear <shadow@dementia.org>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Change-Id: I9c30a9b05fb776bff9b19adf58a701799cce0a27
Reviewed-on: http://gerrit.openafs.org/3566
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>