bug#48611: Allow DEJAGNU TIMEOUT env var for slow arches

[Jacob Bachmeyer]

This patch mentions that the problem seems to be specific to certain 
target architectures and possibly certain testing sites.

Would this be better solved by setting timeouts in a site or board 
configuration file?

I recognize that the remote_exec procedure is not currently sensitive to 
that either, so there will be an enhancement here for 1.6.4 either way.

I will say now that the DEJAGNU_TIMEOUT environment variable will *not* 
be accepted upstream because there are many different timeouts in 
various parts of DejaGnu and providing only a single "knob" to adjust 
all of them is not appropriate.  If there are other components in Debian 
that will need to be updated, I recommend changing the environment 
variable used to DEJAGNU_REMOTE_EXEC_TIMEOUT as an interim measure as 
soon as possible.  That name is acceptable for this purpose, although 
the possibility of instead setting a target configuration parameter is 
likely to be preferred.  There is also little difficulty in allowing an 
environment variable to override a target configuration parameter, for 
ease of development.

Also, does this need to be an environment variable or can it be a 
variable passed on the runtest command line?  (What is the surrounding 
context here?)  The latter would be preferred if feasible simply to 
reduce clutter in the environment:

[...]
+    } elsif { [info exists DEJAGNU_REMOTE_EXEC_TIMEOUT] } {
+        set timeout $DEJAGNU_REMOTE_EXEC_TIMEOUT
[...]

and add "DEJAGNU_REMOTE_EXEC_TIMEOUT=600" to the runtest command line.  
Such variables are set early in runtest.exp while parsing the command 
line but are distinct from the environment.

Backporting patches for this to 1.6.2 and 1.6.3 for Debian should be 
fairly easy once they land on Git master for 1.6.4.


-- Jacob