[ipcz] Fix missing include of <errno.h> on ios

With previous libc++ versions it seems the header got included
transitively by some other header, but that's no longer the case.

Bug: 1423839
Change-Id: Id4049dc5e4807aa0124a17d6289b19155962909e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4334260
Auto-Submit: Hans Wennborg <hans@chromium.org>
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Commit-Queue: Robert Sesek <rsesek@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1116337}
NOKEYCHECK=True
GitOrigin-RevId: 532bc2c8a2328bb70c6e371e20d447d9c38b673c
diff --git a/src/reference_drivers/random.cc b/src/reference_drivers/random.cc
index e228466..6f03842 100644
--- a/src/reference_drivers/random.cc
+++ b/src/reference_drivers/random.cc
@@ -17,7 +17,6 @@
 #include <zircon/syscalls.h>
 #elif BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS) || BUILDFLAG(IS_ANDROID)
 #include <asm/unistd.h>
-#include <errno.h>
 #include <sys/syscall.h>
 #include <unistd.h>
 #elif BUILDFLAG(IS_MAC)
@@ -28,6 +27,7 @@
 #endif
 
 #if BUILDFLAG(IS_POSIX)
+#include <errno.h>
 #include <fcntl.h>
 #include <unistd.h>
 #endif