depcomp: style changes to Portland Group Compilers support * lib/depcomp (pgcc): Quote 'like this', not `like this'. Other minor quoting improvements. Remove a commented-out command. In comments, use proper capitalization and punctuation. Make a more consistent use of whitespace. Make fatal error messages more nicely formatted, and send them to standard error rather than to standard output. Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>