env: Avoid using GNU features in awk

GNU has a very useful third argument to match() but this is not supported
in the POSIX awk.

Update the code to cope, so that the script is POSIX-compliant.

Signed-off-by: Simon Glass <sjg@chromium.org>
Tested-by: Mark Kettenis <mark.kettenis@xs4all.nl>
1 file changed