openssl: fix aix implicit declaration due ...

to header files not shipping declarations.

This seems like a bug in AIX header files because the examples
show including the headers but upon inspecting these files there
are no declarations for sendmmsg and others:

https://www.ibm.com/docs/en/aix/7.2.0?topic=s-sendmmsg-subroutine

For now we can claim to not have these functions.
Alternatively we can declare these ourselves if we are AIX 7.2 or newer.

The actual functions look to be available in libc.

GCC also has the same implicit function declaration but
it happily moves forward.

Clang started making this an explict error in clang 16:

https://www.redhat.com/en/blog/new-warnings-and-errors-clang-16

Author: abmusse

deps/openssl/openssl/crypto/bio/bss_dgram.c

@@ -68,8 +68,8 @@
 #undef NO_RECVMMSG
 #define NO_RECVMMSG
 #endif
-#if defined(_AIX) && !defined(_AIX72)
-/* AIX >= 7.2 provides sendmmsg() and recvmmsg(). */
+#if defined(_AIX)
+/* Force fallback to sndmsg and recvmsg */
 #undef NO_RECVMMSG
 #define NO_RECVMMSG
 #endif