Re: [Libvir] Don't fail to read a file because it's non-seekable (e.g., a pipe).

This fix addresses a problem exposed in an ovirt script whereby trying to use bash process substitution, e.g., in virsh define <(command to generate xml) would fail. Oops. Just noticed that the indentation in the added function (gnulib style) is not consistent with the rest of the file. I'll adjust that before committing, of course. Don't fail to read a file because it's non-seekable (e.g., a pipe). * src/util.c (fread_file_lim): New function. (__virFileReadAll): Use fread_file_lim, rather than requiring that stat.st_size provide a usable file size. * tests/read-non-seekable: New test, for the above. * tests/Makefile.am (test_scripts): Add read-non-seekable. * tests/test-lib.sh (mkfifo_or_skip_): New helper function.