perf probe: Don't always consider EOF as an error when listing source code

When listing a whole file or a function which is located at the end,
perf-probe -L output wrongly: "Source file is shorter than expected.".

This is because show_one_line() always consider EOF as an error.

This patch fixes this by not considering EOF as an error when dumping
the trailing lines. Otherwise it's still an error and perf-probe still
outputs its warning.

Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
LKML-Reference: <1292854685-8230-6-git-send-email-fbuihuu@gmail.com>
Signed-off-by: Franck Bui-Huu <fbuihuu@gmail.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>