init.sh: penalize a set-x-impaired shell; don't disqualify it * tests/init.sh: Too many shells corrupt application stderr when you set -x, so we can't afford to disqualify them, since at least on Irix-6.5, that would disqualify all bourne shells. Instead, use a more discerning approach. When iterating through candidate shells, give each a score of 10 for perfect, 9 if corrupts stderr upon set -x but passes all other tests, and some other value if it is unacceptable. Use the first shell that gets a score of 10. If no shell scores 10, use the first that scored 9. Finally, when VERBOSE=yes is requested and set -x might cause trouble, simply issue a warning and refrain from enabling debug output.