Magic incantation for running multilib testsuite.

[David Daney]

I have tried several times (and failed) to run the GCC testsuite on
multilib targets (x86-64 and mips64) and have not been able to figure
out how to get more that a single multilib configuration to be tested. 
The instructions on http://gcc.gnu.org/install/test.html are not working
for me.  I think I want something like:

$ make -k check  RUNTESTFLAGS="--target_board=unix/{,-m32}"

But that only ends up running unix/-m32

I know that it must be possible as I see the results in gcc-testresults@.

If a kind soul could show the exact command line used to invoke a
combined multilib testsuite run, I would appreciate it.

David Daney