Install Subprocess Utils Header in plugin-headers

Need to use this in plugins

PiperOrigin-RevId: 846375584
Change-Id: Id741a44f162ae32dceed940a1041967b59da71f2
diff --git a/gbmcweb b/gbmcweb
index 469ed14..8cb878b 160000
--- a/gbmcweb
+++ b/gbmcweb
@@ -1 +1 @@
-Subproject commit 469ed144170a1d00b6a41717376085bdc776979e
+Subproject commit 8cb878b5a44b2c756edcb918b4d01d6a20a9d84a