Envsetup: Cygwin doesn't have 'ps -o command'.

Running build/envsetup.sh on cygwin always shows a
warning since there is no 'ps -o command' option.
Bash already sets SHELL=/bin/bash so we can rely on that if present.

Change-Id: I145b42508985735ba61d2b53b216ecc56e321943
1 file changed