CLEANUP: http: fix a build warning introduced by a recent fix

Cyril reported that recent commit 320ec2a ("BUG/MEDIUM: chunks: always
reject negative-length chunks") introduced a build warning because gcc
cannot guess that we can't fall into the case where the auth_method
chunk is not initialized.

This patch addresses it, though for the long term it would be best
if chunk_initlen() would always initialize the result.

This fix must be backported to 1.6 and 1.5 where the aforementionned
fix was already backported.

(cherry picked from commit 5c557d14d54a6d08c8c1624484cd7df2ed3c667e)
(cherry picked from commit 134d8d0d1523c60f90aaf5acb62e377a6c764cca)
1 file changed