fastx: improve ugly 'fgets' hack to avoid compilation warnings.

This change was already included in the previously released
version 0.0.13.2 (but I forgot to add it here).
Enables compiling with "-D_FORTIFY_SOURCE=2".

Solves github issue #1.
Merge branch 'master' into debian/unstable
Call ‘reconf’ before auto-configuration.
Changelog entries.