Mark hidl utils as vndk

As a VNDK module, Android.bp must have 'vndk' tag as well as
'vendor_available: true'.

The 'vndk' tag for VNDK module is formated as below:
vndk: {
    enabled: true,
},

VNDK modules will be installed both in system/lib(64) as normal and
in system/lib(64)/vndk as a vendor variant.

Bug: 63866913
Test: build and boot with BOARD_VNDK_VERSION=current
Change-Id: If0eb0c1bddfa5bdc7ea0ca4635d4e53b59836582

audio/common/2.0/default/Android.bp

@@ -16,6 +16,9 @@
 cc_library_shared {
     name: "android.hardware.audio.common@2.0-util",
     vendor_available: true,
+    vndk: {
+        enabled: true,
+    },
     srcs: [
         "EffectMap.cpp",
         "HidlUtils.cpp",

configstore/utils/Android.bp

@@ -17,6 +17,9 @@
 cc_library_shared {
     name: "android.hardware.configstore-utils",
     vendor_available: true,
+    vndk: {
+        enabled: true,
+    },
     defaults: ["hidl_defaults"],
 
     srcs: [ "ConfigStoreUtils.cpp" ],