feature request: display-expanded AT_CHECK

[Ralf Wildenhues]

It would be very nice to have a command similar to AT_CHECK which
_would_ shell-expand its first argument for display.

For example, in

for flag in '' -foo '-bar opt'
do
  AT_CHECK([$LIBTOOL --mode=compile $CC $flag ...], ...)
done

it would be useful to see the value of $flag.  I don't know if changing
the behavior of AT_CHECK might break things, so I'd suggest another
macro which maybe can share much of the implementation.  Note that the
execution of the command line need not change in any way.

Cheers,
Ralf, still too afraid of m4 fu to be able to hack up a patch