Removed unnecessary ifdef, fixed compiler warning

If WITH_SYNCTEX is not defined, synctex_editor will always be NULL, so
the ifdef is not needed. This gets rid of the "unused variable" warning
when compiling without synctex.

zathura/main.c

@@ -114,12 +114,10 @@ init_zathura(const char* config_dir, const char* data_dir,
     return NULL;
   }
 
-#ifdef WITH_SYNCTEX
   if (synctex_editor != NULL) {
     girara_setting_set(zathura->ui.session, "synctex-editor-command",
                        synctex_editor);
   }
-#endif
 
   return zathura;
 }