Add shell escaping for syslog output

[radosroka]

• fapolicyd attribues are escaped when they are printed to syslog

[stevegrubb]

In escape_shell(), what is expected_size used for? What is the longest length input might be? buffer needs to be at least 4 times it's size. Buffer also might be better off on the heap, meaning a static char [] just above the function for machines with limited stack space.

In format_value(), maybe

if (need_escape)
    out = escape_shell(str, ...
else
   if (asprintf(&out, ...
        out = NULL;

to avoid calling free at all. Also, static analyzers may not be able to reason about whether it needs freeing when "?" is assigned.

[radosroka]

@stevegrubb you can check it now it's little bit cleaner.

[stevegrubb]

OK, looks good.