writerfilter: convert some fprintf to SAL_INFO

Change-Id: I5fe47cfaee84c17584ba7c3d160e65b55f4e3474
rhbz#1065629: RTF import: don't drop nested cells if not enough \cellx

In this document written by "XMLmind XSL-FO Converter" there are less
\cellx than \cell and thus when reading \nestrow/\row a whole buffered
nested table \cell is lost and then subsequently the rest of the nested
table too.  Try to fix that by counting both \cell and \cellx and
replaying until the maximum of those.

Cannot count \intbl since we synthesize that in various places.

(regression in LO 3.5)

Change-Id: I3b64ad94af842e076611418589a0c83bd18841c6