Fix mac build

TBR: fmayer
Change-Id: I6705fdc8706d02bfcd680d965e79f9388f32b4ae
diff --git a/src/base/sock_utils.cc b/src/base/sock_utils.cc
index 2efdbe2..d643d8d 100644
--- a/src/base/sock_utils.cc
+++ b/src/base/sock_utils.cc
@@ -40,7 +40,9 @@
 
 // The CMSG_* macros use NULL instead of nullptr.
 #pragma GCC diagnostic push
+#if !PERFETTO_BUILDFLAG(PERFETTO_OS_MACOSX)
 #pragma GCC diagnostic ignored "-Wzero-as-null-pointer-constant"
+#endif
 
 ssize_t Send(int fd,
              const void* msg,