openvpn: update to 2.5.5
Maintainer: me / @mkrkn
Compile tested: ramips/mt7620 TP-Link Archer C50 v1, ramips/mt7621 Xiaomi Mi router 3 Pro, ath79/generic TP-Link WDR-3500
Run tested: ramips/mt7620 TP-Link Archer C50 v1, ramips/mt7621 Xiaomi Mi router 3 Pro, ath79/generic TP-Link WDR-3500
openvpn: update to 2.5.5
use of CFG Spectre-mitigations in MSVC builds
bring back OpenSSL config loading to Windows builds
several build fixes, refer to https://github.com/OpenVPN/openvpn/blob/release/2.5/Changes.rst
Signed-off-by: Ivan Pavlov <AuthorReflex@gmail.com>