[compiler-rt][sanitizer] fix msghdr for musl

Author: lajosdeak

compiler-rt/lib/sanitizer_common/sanitizer_platform_limits_posix.h

@@ -476,6 +476,39 @@ struct __sanitizer_cmsghdr {
   int cmsg_level;
   int cmsg_type;
 };
+#elif SANITIZER_MUSL
+struct __sanitizer_msghdr {
+  void *msg_name;
+  unsigned msg_namelen;
+  struct __sanitizer_iovec *msg_iov;
+#  if __LONG_MAX > 0x7fffffff && __BYTE_ORDER == __BIG_ENDIAN
+  int __pad1;
+#  endif
+  int msg_iovlen;
+#  if __LONG_MAX > 0x7fffffff && __BYTE_ORDER == __LITTLE_ENDIAN
+  int __pad1;
+#  endif
+  void *msg_control;
+#  if __LONG_MAX > 0x7fffffff && __BYTE_ORDER == __BIG_ENDIAN
+  int __pad2;
+#  endif
+  unsigned msg_controllen;
+#  if __LONG_MAX > 0x7fffffff && __BYTE_ORDER == __LITTLE_ENDIAN
+  int __pad2;
+#  endif
+  int msg_flags;
+};
+struct __sanitizer_cmsghdr {
+#  if __LONG_MAX > 0x7fffffff && __BYTE_ORDER == __BIG_ENDIAN
+  int __pad1;
+#  endif
+  unsigned cmsg_len;
+#  if __LONG_MAX > 0x7fffffff && __BYTE_ORDER == __LITTLE_ENDIAN
+  int __pad1;
+#  endif
+  int cmsg_level;
+  int cmsg_type;
+};
 #else
 // In POSIX, int msg_iovlen; socklen_t msg_controllen; socklen_t cmsg_len; but
 // many implementations don't conform to the standard.