Add bluetooth build config for mainline

This matches the build config used on current mainline devices,
but should ideally be removed once possible.

Bug: 123695868
Test: boot blueline
Change-Id: I8fdef9fbe45b75f175afe9350974f54d1ec5e0c8
diff --git a/target/board/BoardConfigMainlineCommon.mk b/target/board/BoardConfigMainlineCommon.mk
index 9a4fb3a..e87bd5e 100644
--- a/target/board/BoardConfigMainlineCommon.mk
+++ b/target/board/BoardConfigMainlineCommon.mk
@@ -31,5 +31,9 @@
 # Audio: must using XML format for Treblized devices
 USE_XML_AUDIO_POLICY_CONF := 1
 
+# Bluetooth defines
+# TODO(b/123695868): Remove the need for this
+BOARD_BLUETOOTH_BDROID_BUILDCFG_INCLUDE_DIR := build/make/target/board/mainline_arm64/bluetooth
+
 BOARD_AVB_ENABLE := true
 BOARD_AVB_ROLLBACK_INDEX := $(PLATFORM_SECURITY_PATCH_TIMESTAMP)