BUG/MAJOR: Fix crash in http_get_fhdr with exactly MAX_HDR_HISTORY headers

Similar issue was fixed in 67dad27, but the fix is incomplete. Crash still
happened when utilizing req.fhdr() and sending exactly MAX_HDR_HISTORY
headers.

This fix needs to be backported to 1.5 and 1.6.

Signed-off-by: Nenad Merdanovic <nmerdan@anine.io>
(cherry picked from commit 69ad4b997701b08e9de48fce4dc4ceeb7d80cb32)
(cherry picked from commit dc422d0f091210e4121d4f862e79396d0e69e243)
1 file changed