scripts/functions: fix debug-shell

Properly catch resuming the build when continuing past the
failed command.

The 'case ;;&' construct is a bash4ism. Get rid of it.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

reporter_name="Alexander BIGGA"

reporter_url="http://sourceware.org/ml/crossgcc/2008-07/msg00000.html"

reporter_comment=""