Make fop less verbose when building PDF

Hi,

When building the pdf docs, fop emits a line for each page of the docs:
> ...
> [INFO] FOUserAgent - Rendered page #2931.

which, given the length of our docs, makes the output pretty pointless. Even
if there are warnings, one likely won't notice them.

I just figured out that one can hide those. Unfortunately not at the
commandline, but in "$HOME/.foprc" or /etc.

$ cat ~/.foprc
LOGLEVEL=-Dorg.apache.commons.logging.simplelog.defaultlog=WARN

makes it a lot less annoying. And one can see that we currently are getting
warnings:

[warning] /usr/bin/fop: JVM flavor 'sun' not understood
[WARN] FOUserAgent - Font "Symbol,normal,700" not found. Substituting with "Symbol,normal,400".
[WARN] FOUserAgent - Font "ZapfDingbats,normal,700" not found. Substituting with "ZapfDingbats,normal,400".
[WARN] FOUserAgent - The contents of fo:block line 2 exceed the available area in the inline-progression direction by more than 50 points. (See position 30429:383)
[WARN] PropertyMaker - span="inherit" on fo:block, but no explicit value found on the parent FO.

The first is a debianism, the next two are possibly spurious [1]. But the next
two might be relevant?


I don't immediately see a way that's not too gross (like redefining HOME when
invoking fop) to set LOGLEVEL without editing .foprc.  Perhaps we should add
advice to do so to docguide.sgml?

Greetings,

Andres Freund

[1] https://lists.apache.org/thread/yqkjzow3y8fpo9fc3hlbqb9fk49fonlf