vl: fix breakage of -tb-size

Commit e7b161d ("vl: add tcg_enabled() for tcg related code") adds
a check to exit the program when !tcg_enabled() while parsing the -tb-size
flag.

It turns out that when the -tb-size flag is evaluated, tcg_enabled() can
only return 0, since it is set (or not) much later by configure_accelerator().

Fix it by unconditionally exiting if the flag is passed to a QEMU binary
built with !CONFIG_TCG.

Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

vl.c

@@ -3933,10 +3933,10 @@ int main(int argc, char **argv, char **envp)
                 configure_rtc(opts);
                 break;
             case QEMU_OPTION_tb_size:
-                if (!tcg_enabled()) {
-                    error_report("TCG is disabled");
-                    exit(1);
-                }
+#ifndef CONFIG_TCG
+                error_report("TCG is disabled");
+                exit(1);
+#endif
                 if (qemu_strtoul(optarg, NULL, 0, &tcg_tb_size) < 0) {
                     error_report("Invalid argument to -tb-size");
                     exit(1);