ppp: update to 2.5.0

ppp: update to 2.5.0

ChangeLog:
https://github.com/ppp-project/ppp/blob/ppp-2.5.0/ChangeLog

Upstreamed patches:
120-debian_ipv6_updown_option.patch [1]
133-fix_sha1_include.patch [2]
140-pppd-Fix-compilation-with-older-glibc-or-kernel-head.patch [3]
141-Expand-byte-count-statistics-to-64-bits-298.patch [4]
142-pppd-Add-support-for-registering-ppp-interface-via-L.patch [5]
143-pppd-Workaround-for-generating-ppp-unit-id-on-Linux-.patch [6]
144-pppd-Retry-registering-interface-when-on-rtnetlink-E.patch [7]

Suppressed patches:
200-makefile.patch [8]
201-mppe_mppc_1.1.patch [9]
203-opt_flags.patch [10]
300-filter-pcap-includes-lib.patch [11]
511-pptp_cflags.patch [12]
600-Revert-pppd-Use-openssl-for-the-DES-instead-of-the-l.patch [13]
610-pppd_compile_fix.patch [14]

[1] https://github.com/ppp-project/ppp/commit/7f8c1a1f8e486b232340fd9a0a19c5d34f1c5ae0
[2] https://github.com/ppp-project/ppp/commit/ba7f7e053daae846a54a1d08d3d133a5f1266ace
[3] https://github.com/ppp-project/ppp/commit/98ec18f098e5ef68e3a8cc6954fcaf5a7fb8b7be
[4] https://github.com/ppp-project/ppp/commit/81ad945630120cc1c27c8bb00503be42b76ff202
[5] https://github.com/ppp-project/ppp/commit/4a54e34cf5629f9fed61f0b7d69ee3ba4d874bc6
[6] https://github.com/ppp-project/ppp/commit/44609bfc974bdafc0316d069aabf5e2903efa805
[7] https://github.com/ppp-project/ppp/commit/089687fbcc6524809ae9f4b2f8145fe3c2a91147
[8] enable_eaptls=no, with_pcap=no, HAVE_CRYPT_H=1 in configure
[9] enable_microsoft_extensions=yes, MPPC support is removed.
[10] fPIC ignored so far
[11] done by autotools
[12] in main patch for pptp plugin
[13] with_openssl=no, already in upstream ppp-des.c
[14] with_static_pcap=yes from patch 310

Signed-off-by: Sergey Ivanov <icegood1980@gmail.com>
* Fix package hash.
* Fix multilink variant build.
* Fix some compile errors.
* Some code format fixes.
* Refactor commit message.
* Rebase git and fix conflicts.

Co-authored-by: Shiji Yang <yangshiji66@qq.com>
Signed-off-by: Shiji Yang <yangshiji66@qq.com>
Link: https://github.com/openwrt/openwrt/pull/16605
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>