[rkp] Build MACed public key from boringssl EC_KEY

The secret will be added in a subsequent after we get the DICE
chain info of the RKP VM.

Bug: 300068317
Test: atest rialto_test
Change-Id: Ia373930fc8f1c6d38349208ca62b9b71b98d126f
diff --git a/rialto/Android.bp b/rialto/Android.bp
index cb3e477..96b9b10 100644
--- a/rialto/Android.bp
+++ b/rialto/Android.bp
@@ -12,6 +12,7 @@
         "libbssl_ffi_nostd",
         "libciborium_io_nostd",
         "libciborium_nostd",
+        "libcoset_nostd",
         "libdiced_open_dice_nostd",
         "libdiced_sample_inputs_nostd",
         "libhyp",