tests: only build plugins if TCG is enabled

There is no way to use them for testing, if all the available
accelerators use hardware virtualization.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20240408155330.522792-3-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tests/meson.build

@@ -78,9 +78,9 @@ subdir('decode')
 
 if 'CONFIG_TCG' in config_all_accel
   subdir('fp')
+  subdir('plugin')
 endif
 
-subdir('plugin')
 subdir('unit')
 subdir('qapi-schema')
 subdir('qtest')