[PATCH] PR20721: Don't let UBSan print inaccessible memory

[Yury Gribov]

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Comment at: lib/sanitizer_common/sanitizer_posix_libcdep.cc:177
@@ +176,3 @@
+  bool res =
+      !internal_iserror(bytes_written, &write_errno) && bytes_written == size;
+  internal_close(sock_pair[0]);
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Perhaps assert that write_errno == EFAULT in case of error?

http://reviews.llvm.org/D5253