Draft: community/php8: upgrade to 8.1.0-rc3

This MR is for testing upcoming version https://wiki.php.net/todo/php81

DO NOT MERGE! part of #12966 (closed)

current issues

• multiple SAPI build is not possible - at least apache2 and embed fails https://gist.github.com/andypost/23e341a4e5afd29d1779393403958a69

• linking fails sometimes, so removal of modules/* helped !22236 (comment 169645) (also fixable with -j1 or -j2 for make)

Warning: PHP Startup: Unable to load dynamic library 'modules/pdo_dblib.so' (tried: modules/pdo_dblib.so (Error relocating modules/pdo_dblib.so: dbversion: symbol not found), /usr/lib/php8/modules/modules/pdo_dblib.so.so (Error loading shared library /usr/lib/php8/modules/modules/pdo_dblib.so.so: No such file or directory)) in Unknown on line 0

• test failures -- armhf 2 !22236 (comment 172424)

Hash: hash_copy() via clone [ext/hash/tests/hash-clone.phpt]
Hash: hash_copy() basic tests [ext/hash/tests/hash_copy_001.phpt]

-- riscv64

Bug #78808 ([LMDB] MDB_MAP_FULL: Environment mapsize limit reached) [ext/dba/tests/bug78808.phpt]
DBA LMDB handler test [ext/dba/tests/dba_lmdb.phpt]
Bug #63000: Multicast on OSX [ext/sockets/tests/bug63000.phpt]
mixed socket_getopt( resource $socket , int $level , int $optname ) ; [ext/sockets/tests/socket_getopt.phpt]
Error during socket_sendmsg() or socket_recvmsg() [ext/sockets/tests/socket_sendrecvmsg_error.phpt]