Error cases in base collectives

[abouteiller]

This patch fixes the following defects in cases where errors are reported by a collective operation:

1. Make sure we deallocate internal requests when the collective completes in error
2. Make sure we return a useful error from the collective (rather than non-descriptive 'error-in-status' or 'error-pending')
3. Handle cases where the barrier algorithms are called with 1 proc (typically from internal operations).

Signed-off-by: Aurelien Bouteiller [email protected]

[bwbarrett]

bot:ompi:retest

stupid disk space failures