how to combine make check options?

[Jack Howarth]

    Is it possible to combine different options together when
running the testsuite? For example I can run...

make check-objc RUNTESTFLAGS="--target_board=unix/-fgnu-runtime"

and

make check-objc RUNTESTFLAGS='--target_board="unix{,-m64}"'

However I don't see how to combine this so that both
-m32 and -m64 testsuite runs will occur that both also
use -fgnu-runtime. Thanks in advance or any suggestions.
               Jack