s3-debug Convert from x_file to real file descriptors.

s3-debug Convert from x_file to real file descriptors.

X_FILE does not gain us anything in this use case, we want our log
messages on disk, not in a buffer, and we don't gain anything from the
X_FILE api.  I discussed the matter with tridge, who feels that to use
FILE in the first place was a mistake, and that X_FILE isn't any
better, but was a stop-gap to avoid issues on solaris.

Andrew Bartlett