BUG #1741: %i missing in snprintf implementation

The following bug has been logged online:

Bug reference: 1741
Logged by: Tim Mauch
Email address: tgmauch(at)yahoo(dot)com
PostgreSQL version: 8.0.1 - 8.0.3
Operating system: Redhat linux 8.0
Description: %i missing in snprintf implementation
Details:

The implementation of snprintf/vsnprintf in src/port/snprintf.c does not
allow the use of %i ( %d equivalent ). This likely isn't a problem for
postgres itself, but when a program compiles with -lpq and the standard c
libraries are not previously included the use of %i in the format string of
snprintf causes segmentation faults.

This is easily fixed by adding "case 'i':" to the same block of code handled
by "case 'd':" and case 'D':" in the implementation.