Export the libbinder flag to Android.bp

Note that the namespace is "libbinder".

Bug: 333854840
Test: N/A
Flag: RELEASE_LIBBINDER_CLIENT_CACHE
Change-Id: Iecfb62c14685afcce72cf89ad61536efd2d17e31
diff --git a/target/product/build_variables.mk b/target/product/build_variables.mk
index 5fe5333..9fc9ff9 100644
--- a/target/product/build_variables.mk
+++ b/target/product/build_variables.mk
@@ -17,5 +17,8 @@
 # This file contains the trunk-stable flags that should be exported to all
 # Android targets.
 
+# Control libbinder client caching
+$(call soong_config_set, libbinder, release_libbinder_client_cache, $(RELEASE_LIBBINDER_CLIENT_CACHE))
+
 # Use the configured release of sqlite
 $(call soong_config_set, libsqlite3, release_package_libsqlite3, $(RELEASE_PACKAGE_LIBSQLITE3))