system/cpu-timers: Have icount_configure() return a boolean

Following the example documented since commit e3fe3988d7 ("error:
Document Error API usage rules"), have icount_configure()
return a boolean indicating whether an error is set or not.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20231208113529.74067-2-philmd@linaro.org>

stubs/icount.c

@@ -10,10 +10,12 @@ void icount_update(CPUState *cpu)
 {
     abort();
 }
-void icount_configure(QemuOpts *opts, Error **errp)
+bool icount_configure(QemuOpts *opts, Error **errp)
 {
     /* signal error */
     error_setg(errp, "cannot configure icount, TCG support not available");
+
+    return false;
 }
 int64_t icount_get_raw(void)
 {