Review 13935

C. Thomas Tyler
Added settings for P4TRUST and P4ENVIRO to both Linux and Windows environments.
Removed '#!/bin/bash' line from to of p4_vars.tempate, as the generarted p4_vars
file is intended to be sourced rather than executed directly (and to avoid
starting an unnecessary subshell).

Also removed execute bit (undoing 'chmod +x') from p4_vars.template, just to
emphaisze its intended use.
#1: Change 13934 committed into //guest/perforce_software/sdp/dev/Server 2 0 0
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