test: Run fuzz tests on macOS

Also, fix a few bugs:

* Error: RPC command "enumeratesigners" not found in RPC_COMMANDS_SAFE_FOR_FUZZING or RPC_COMMANDS_NOT_SAFE_FOR_FUZZING. Please update test/fuzz/rpc.cpp.
* in run_once: ...format(" ".join(result.args), ... TypeError: sequence item 2: expected str instance, PosixPath found

test/config.ini.in

@@ -22,7 +22,7 @@ RPCAUTH=@abs_top_srcdir@/share/rpcauth/rpcauth.py
 @BUILD_BITCOIN_UTIL_TRUE@ENABLE_BITCOIN_UTIL=true
 @BUILD_BITCOIN_WALLET_TRUE@ENABLE_WALLET_TOOL=true
 @BUILD_BITCOIND_TRUE@ENABLE_BITCOIND=true
-@ENABLE_FUZZ_TRUE@ENABLE_FUZZ=true
+@ENABLE_FUZZ_BINARY_TRUE@ENABLE_FUZZ_BINARY=true
 @ENABLE_ZMQ_TRUE@ENABLE_ZMQ=true
 @ENABLE_EXTERNAL_SIGNER_TRUE@ENABLE_EXTERNAL_SIGNER=true
 @ENABLE_SYSCALL_SANDBOX_TRUE@ENABLE_SYSCALL_SANDBOX=true