Add header to build.json
diff --git a/build.json b/build.json
index 4c800a2..bdc167e 100644
--- a/build.json
+++ b/build.json
@@ -315,6 +315,7 @@
         "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",