util: Consolidate and improve workarounds for clang-tidy issue 58992

We have several workarounds for a clang-tidy bug where the checker doesn't
recognize that a number of system calls write to - and therefore initialise
- a socket address.  We can't neatly use a suppression, because the bogus
warning shows up some time after the actual system call, when we access
a field of the socket address which clang-tidy erroneously thinks is
uninitialised.

Consolidate these workarounds into one place by using macros to implement
wrappers around affected system calls which add a memset() of the sockaddr
to silence clang-tidy.  This removes the need for the individual memset()
workarounds at the callers - and the somewhat longwinded explanatory
comments.

We can then use a #define to not include the hack in "real" builds, but
only consider it for clang-tidy.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

icmp.c

@@ -76,11 +76,6 @@ void icmp_sock_handler(const struct ctx *c, union epoll_ref ref)
 	if (c->no_icmp)
 		return;
 
-	/* FIXME: Workaround clang-tidy not realizing that recvfrom()
-	 * writes the socket address.  See
-	 * https://github.com/llvm/llvm-project/issues/58992
-	 */
-	memset(&sr, 0, sizeof(sr));
 	n = recvfrom(ref.fd, buf, sizeof(buf), 0, (struct sockaddr *)&sr, &sl);
 	if (n < 0)
 		return;