PATCH: add --local_init and --global_init options to override use of site.exp

I had been planning to sit on this a bit longer and submit it with the rest of the Automake integration fixes, but that has turned out to be more involved than initially expected, so here is the patch for adding --local_init and --global_init options. Adding tests for these is on my local TODO

Code and comments in runtest.exp that do not match

While adding --{loc,glob}al_init options to runtest, I ran across this code: = at line 865 in master:runtest.exp if { [load_file -- $env(DEJAGNU)] == 0 } { # It may seem odd to only issue a warning if there isn't a global # config file, but issue an error if $DEJAGNU is erroneo