Merge pull request #13574 from vjpai/bazel_fix

Somehow fork.h got omitted from BUILD

BUILD

@@ -79,10 +79,11 @@ GRPC_PUBLIC_HDRS = [
     "include/grpc/byte_buffer.h",
     "include/grpc/byte_buffer_reader.h",
     "include/grpc/compression.h",
-    "include/grpc/load_reporting.h",
+    "include/grpc/fork.h",
     "include/grpc/grpc.h",
     "include/grpc/grpc_posix.h",
     "include/grpc/grpc_security_constants.h",
+    "include/grpc/load_reporting.h",
     "include/grpc/slice.h",
     "include/grpc/slice_buffer.h",
     "include/grpc/status.h",