use strncat instead of sprintf

git-svn-id: http://svn.osgeo.org/postgis/branches/2.1@12515 b70326c6-7e19-0410-871a-916f4a2858ee
snprintf instead of sprintf

git-svn-id: http://svn.osgeo.org/postgis/branches/2.1@12516 b70326c6-7e19-0410-871a-916f4a2858ee
set first byte to null

git-svn-id: http://svn.osgeo.org/postgis/branches/2.1@12518 b70326c6-7e19-0410-871a-916f4a2858ee