Update rustflags to work with new hal_v4 types

Bug: 369375199
Test: treehugger
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:4daa65d001fa74dfea32df06daf61171bee2c3dc)
Merged-In: I5ebea2568301d6bc61783f18829ae0fb386a7fc3
Change-Id: I5ebea2568301d6bc61783f18829ae0fb386a7fc3

lib/keymint-rust/wire/rules.mk

diff --git a/lib/keymint-rust/wire/rules.mk b/lib/keymint-rust/wire/rules.mk
index c96467b..052a273 100644
--- a/lib/keymint-rust/wire/rules.mk
+++ b/lib/keymint-rust/wire/rules.mk
@@ -24,6 +24,7 @@
 MODULE_RUSTFLAGS += \
 	--cfg 'feature="hal_v2"' \
 	--cfg 'feature="hal_v3"' \
+	--cfg 'feature="hal_v4"' \
 
 MODULE_LIBRARY_EXPORTED_DEPS += \
 	$(call FIND_CRATE,enumn) \