pgsql: Truncate strings in tarCreateHeader() with strlcpy(), not sprint

Truncate strings in tarCreateHeader() with strlcpy(), not sprintf().

This supplements the GNU libc bug #6530 workarounds introduced in commit
54cd4f04576833abc394e131288bf3dd7dcf4806.  On affected systems, a
tar-format pg_basebackup failed when some filename beneath the data
directory was not valid character data in the postmaster/walsender
locale.  Back-patch to 9.1, where pg_basebackup was introduced.  Extant,
bug-prone conversion specifications receive only ASCII bytes or involve
low-importance messages.

Branch
------
REL9_4_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/d1c1e48832f31c1a4d01201a31a60c751ed4895c

Modified Files
--------------
src/bin/pg_basebackup/t/010_pg_basebackup.pl |    8 ++++++++
src/port/tar.c                               |    8 ++++----
2 files changed, 12 insertions(+), 4 deletions(-)