pathchk info page should mention other leading brand

[jidanni]

$ info cor pathchk
When I read this info page the question that one asks is "What about
Windows? I want to know if I zip up some files and give them to my
friend, will there be some problem when he unzips them on Windows?"

So perhaps add after
       3. A file name contains a character outside the portable file
          name character set, namely, the ASCII letters and digits, `-',
          `.', `/', and `_'.
"So the filename should be portable to Windows, Mac..."

(But not MS-DOS "8.3 names" of course.)

Anyway,
  2. The length of NAME is larger than the maximum supported by the
     operating system.

  3. The length of one component of NAME is longer than its file
     system's maximum.

but the OS would have warned us.

   A nonexistent NAME is not an error, so long a file with that name
   could be created under the above conditions.

I see, it is for testing before making files on the current system...
but then we could just do "touch FUNNY_NAME" and if we get an error
message we will know usually... mainly we want to know if a file is
portable to a foreign systems that we have no access to. OK, whatever.
Do mention Windows...

Also note that it writes to stderr, not stdout.

Also mention that for each filename it bails out on the first error,
# pathchk -p 123456789012345
pathchk: limit 14 exceeded by length 15 of file name component `123456789012345'
# pathchk -p 123456789012345+
pathchk: nonportable character `+' in file name `123456789012345+'
# pathchk -p 123456789012345+=
pathchk: nonportable character `+' in file name `123456789012345+='
# pathchk -p 123456789012345=+
pathchk: nonportable character `=' in file name `123456789012345=+'
so it can take multiple runs to find them all...