Add header to build.json
diff --git a/BUILD b/BUILD
index 11285c2..7bbbe2f 100644
--- a/BUILD
+++ b/BUILD
@@ -101,6 +101,7 @@
     "include/grpc/support/port_platform.h",
     "include/grpc/support/slice.h",
     "include/grpc/support/slice_buffer.h",
+    "include/grpc/support/subprocess.h",
     "include/grpc/support/sync.h",
     "include/grpc/support/sync_generic.h",
     "include/grpc/support/sync_posix.h",