Specify keystore dependency on libhardware_headers

Emulator keystore HAL uses headers from libhardware_headers
without specifying this VNDK dependency in its Android.mk,
so the build will break when BOARD_VNDK_VERSION := current.

Bug: 65435048
Test: lunch aosp_x86; m -j; emulator # boot to home screen
Change-Id: Ia47e1cd4cf88ed00d64f43700eda556f437a9843
diff --git a/keymaster/Android.mk b/keymaster/Android.mk
index 7203c47..e6c7b22 100644
--- a/keymaster/Android.mk
+++ b/keymaster/Android.mk
@@ -15,5 +15,6 @@
                     $(LOCAL_PATH)/../include
 LOCAL_CFLAGS = -fvisibility=hidden -Wall -Werror
 LOCAL_SHARED_LIBRARIES := libcrypto liblog libsoftkeymasterdevice libkeymaster_messages libcutils
+LOCAL_HEADER_LIBRARIES := libhardware_headers
 LOCAL_MODULE_TAGS := optional
 include $(BUILD_SHARED_LIBRARY)