pgsql: to_char(): prevent writing beyond the allocated buffer

to_char():  prevent writing beyond the allocated buffer

Previously very long localized month and weekday strings could
overflow the allocated buffers, causing a server crash.

Reported and patch reviewed by Noah Misch.  Backpatch to all
supported versions.

Security: CVE-2015-0241

Branch
------
REL9_0_STABLE

Details
-------
http://git.postgresql.org/pg/commitdiff/56b970f2e98853bee7205022df4c5d38bafacdf5

Modified Files
--------------
src/backend/utils/adt/formatting.c |  141 ++++++++++++++++++++++++++++++++----
1 file changed, 126 insertions(+), 15 deletions(-)