android: Skip unknown ABIs when building OpenSSL

Newer NDKs have RISC-V as experimental ABI (not enabled by default, see
next commit).  If we don't have a mapping for a specific target, OpenSSL
falls back to 'android-arm', so that won't really work (interestingly,
it does build).

src/frontends/android/openssl/compile.sh

@@ -35,6 +35,10 @@ x86)
 x86_64)
 	OPTIONS="android-x86_64"
 	;;
+*)
+	echo "!! Skipping unknown ABI '${ABI}'"
+	continue
+	;;
 esac
 
 OPTIONS="${OPTIONS} \