devel/cproto: Update 4.7y => 4.8

Changelog:
2026/05/12 (4.8)

• modify --with-trace option to separate it from doalloc(), which is now a configure option --enable-doalloc
• add __int128 and other gcc extensions to keywords (Debian #1121161)
• improve configure script checks, reducing warnings
• update config.guess, config.sub

https://invisible-island.net/cproto/CHANGES.html#index-t20260512

Also drops files/patch-system.h, which is obsoleted by AC_PROG_CPP
in upstream's configure.in. autoconf now detects "cc -E" on FreeBSD
at configure-time and writes it into config.h, which is semantically
better than the hardcoded /usr/bin/cpp the downstream patch provided.

PR: 295264
Sponsored by: UNIS Labs