pgstatsinfo - pg_statsinfo: Add error checks to write and fwrite calls.

Log Message:
-----------
Add error checks to write and fwrite calls.

Modified Files:
--------------
pg_statsinfo/bin:
logger.c (r1.20 -> r1.21)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pgstatsinfo/pg_statsinfo/bin/logger.c?r1=1.20&r2=1.21)
logger_out.c (r1.6 -> r1.7)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pgstatsinfo/pg_statsinfo/bin/logger_out.c?r1=1.6&r2=1.7)
pg_statsinfo.h (r1.13 -> r1.14)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pgstatsinfo/pg_statsinfo/bin/pg_statsinfo.h?r1=1.13&r2=1.14)
pg_statsinfo/lib:
libstatsinfo.c (r1.17 -> r1.18)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pgstatsinfo/pg_statsinfo/lib/libstatsinfo.c?r1=1.17&r2=1.18)