MINOR: cfgparse: Warn on truncated lines / files

As discussed on the list: https://www.mail-archive.com/haproxy@formilux.org/msg37698.html

This patch adds warnings to the configuration parser that detect the
following situations:

- A line being truncated by a null byte in the middle.
- A file not ending in a new line (and possibly being truncated).
1 file changed