test/trace_api_test.c: fix gcc error on -Werror=strict-prototypes

Reviewed-by: NTomas Mraz <tomas@openssl.org>
Reviewed-by: NTodd Short <todd.short@me.com>
Reviewed-by: NDavid von Oheimb <david.von.oheimb@siemens.com>
(Merged from https://github.com/openssl/openssl/pull/19277)

test/trace_api_test.c

@@ -67,7 +67,7 @@ static int test_trace_categories(void)
 }
 
 #ifndef OPENSSL_NO_TRACE
-static void put_trace_output()
+static void put_trace_output(void)
 {
     OSSL_TRACE_BEGIN(TLS) {
         BIO_printf(trc_out, "Hello World\n");
@@ -75,7 +75,7 @@ static void put_trace_output()
     } OSSL_TRACE_END(TLS);
 }
 
-static int test_trace_channel()
+static int test_trace_channel(void)
 {
     static const char expected[] = "xyz-\nHello World\nGood Bye Universe\n-abc\n";
     static const char expected_len = sizeof(expected) - 1;