Add a build-timeout macro

This change adds a build-timeout macro.  This macro sets two parameters
1. sets a 'BUILD_TIMEOUT' environment variable which is set to the
   build timeout value.
2. sets the build to a failed state when a timeout has occurred.

This change requires the Jenkins build-timeout plugin >= ver 1.13
It will not work with older versions of the plugin.  When this parameter
is used with version 1.10 of the plugin Jenkins will set the timeout to 0
and abort builds immediately.

Change-Id: Ie261cac10b59a6094a7f3ec9167274c47b2fc4a3
Merge "Add a build-timeout macro"